Optical communications module link extender, and related systems and methods

ABSTRACT

This disclosure describes devices and methods related to multiplexing optical datasignals. A method may be disclosed. The method may comprise receiving, by a dense wave division multiplexer (DWDM), one or more optical data signals. The method may comprise combining, by the DWDM, the one or more optical data signals. The method may comprise outputting, by the DWDM, the combined one or more optical data signals to a first circulator. The method may also comprise combining, by the WDM, the second optical data signal and one or more third signals, and outputting an egress optical data signal to an optical switch. The method may also comprise outputting, by the optical switch, the egress optical data signal on a primary fiber.

FIELD OF INVENTION

This disclosure relates generally to the field of opticaltelecommunications and includes an integrated module with severalsub-assemblies.

BACKGROUND

To understand the importance of optical networking, the capabilities ofthis technology have to be discussed in the context of the challengesfaced by the telecommunications industry, and, in particular, serviceproviders. Most U.S. networks were built using estimates that calculatedbandwidth use by employing concentration ratios derived from classicalengineering formulas for modeling network usage such as the Poissonprocess. Consequently, forecasts of the amount of bandwidth capacityneeded for data networks were calculated on the presumption that a givenindividual would only use network bandwidth six minutes of each hour.These formulas did not factor in the amount of traffic generated bydifferent devices accessing the Internet. With the advent of theInternet and the ever increasing number of devices (e.g., facsimilemachines, multiple phone lines, modems, teleconferencing equipment,mobile devices including smart phones, tablets, laptops, wearabledevices, and Internet of Things (IoT) devices, etc.) accessing theInternet, there has been an average increase in Internet traffic of 300percent year over year. Had these factors been included, a far differentestimate would have emerged.

As a result of this explosive growth of devices, an enormous amount ofbandwidth capacity is required to provide the services required by thesedevices. In the 1990s, some long-distance carriers increased theircapacity (bandwidth) to 1.2 Gbps over a single optical fiber pair, whichwas a considerable upgrade at the time. At a transmission speed of oneGbps, one thousand books can be transmitted per second. However today,if one million families in a city decided to view a video on a Web site(e.g., YouTube, Home Box Office (HBO) on the go, DirectTV, etc.) thennetwork transmission rates on the order of terabits are required. With atransmission rate of one terabit, it is possible to transmit 200 millionsimultaneous full duplex phone calls or transmit the text from 300years-worth of daily newspapers per second.

When largescale data networks providing residential, commercial, andenterprise customers with Internet access were first deployed, theunprecedented growth in the number of devices accessing the networkcould not have been imagined. As a result, the network growthrequirements needed in order to meet the demand of the devices were notconsidered at that time either. For example, from 1994 to 1998, it isestimated that the demand on the U.S. interexchange carriers' (IXC's)network would increase sevenfold, and for the U.S. local exchangecarriers' (LEC's) network, the demand would increase fourfold. Forinstance, some cable companies indicated that their network growth was32 times the previous year, while other cable companies have indicatedthat the size of their networks have doubled every six months in afour-year period.

In addition to this explosion in consumer demand for bandwidth, manyservice provider are coping with optical fiber exhaust in their network.For example, in 1995 alone many (ISP) companies indicated that theamount of embedded optical fibers already in use at the time was between70 percent and 80 percent (i.e., 70 to 80 percent of the capacity oftheir networks were used the majority of the time to provide service tocustomers). Today, many cable companies are nearing one hundred percentcapacity utilization across significant portions of their networks.Another problem for cable companies is the challenge of deploying andintegrating diverse technologies in on physical infrastructure. Customerdemands and competitive pressures mandate that carriers offer diverseservices economically and deploy them over the embedded network. Onepotential technology that meets these requirements is based onmultiplexing a large and diverse number of data, regardless of the typeof data, onto a beam of light that may be attenuated to propagate atdifferent wavelengths. The different types of data may comprisefacsimile sources, landline voice sources, voice over Internet Protocol(VOIP) sources, video sources, web browser sources, mobile devicesources including voice application sources, short messaging service(SMS) application sources, multimedia messaging service (MMS)application sources, mobile phone third party application (app) sources,and/or wearable device sources. When a large and diverse number of datasources, such as the ones mentioned in the previous sentence, aremultiplexed together over light beams transmitted on an optical fiber,it may be referred to as a dense wave division multiplexing (DWDM).

The use of an optical communications module link extender (OCML) circuitas described herein allows cable companies to offer these servicesregardless of the open systems interconnection (OSI) model network layer(layer 3) protocols or media access control (MAC) (layer 2) protocolsthat are used by the different sources to transmit data. For example,e-mail, video, and/or multimedia data such as web based content data,may generate IP (layer 3) data packets that are transmitted inasynchronous transfer mode (ATM) (layer 2) frames. Voice (telephony)data may be transmitted over synchronous optical networking(SONET)/synchronous digital hierarchy (SDH). Therefore regardless ofwhich layer is generating data (e.g., IP, ATM, and/or SONET/SDH) a DWDMpassive circuit provides unique bandwidth management by treating alldata the same. This unifying capability allows cable companies with theflexibility to meet customer demands over a self-contained network.

A platform that is able to unify and interface with these technologiesand position the cable company with the ability to integrate current andnext-generation technologies is critical for a cable company's success.

Cable companies faced with the multifaceted challenge of increasedservice needs, optical fiber exhaust, and layered bandwidth management,need options to provide economical and scalable technologies. One way toalleviate optical fiber exhaust is to lay more optical fiber, and, forthose networks where the costs of laying new optical fiber is minimal,the best solution may be to lay more optical fiber. This solution maywork in more rural, where there may be no considerable populationgrowth. However, in urban or suburban areas laying new optical fiber maybe costly. Even if it was not costly, the mere fact that more cable isbeing laid does not necessarily enable a cable company to provide newservices or utilize the bandwidth management capabilities of theunifying optical transmission mechanism such as DWDM.

Another solution may be to increase the bit rate using time divisionmultiplexing (TDM). TDM increases the capacity of an optical fiber byslicing time into smaller time intervals so that more bits of data canbe transmitted per second. Traditionally, this solution has been themethod of choice, and cable companies have continuously upgraded theirnetworks using different types of digital signaling technologies tomultiplex data over SONET/SDH networks. For example, Digital Signal (DS)DS-1, DS-2, DS-3, DS-4, and DS-5, commonly referred to as T1, T2, T3,T4, or T5 lines, are different carrier signals, that are transmittedover SONET/SDH networks that can carry any of the sources of datamentioned above, whose data rates increase with the number assigned tothe DS. That is DS-1 was the earliest carrier signal used to transmitdata over SONET/SDH networks, and has the lowest data rate and DS-5 isthe most recent carrier signal use to transmit data over SONET/SDHnetworks with the highest data rate. Cable company networks, especiallySONET/SDH networks have evolved over time to increase the number of bitsof data that can be transmitted per second by using carrier signals withhigher data rates. However, when cable companies use this approach, theymust purchase capacity based on what the SONET/SDH standard dictateswill be the next increase in capacity. For example, cable companies canpurchase a capacity of 10 Gbps for TDM, but should the capacity not beenough the cable companies will have to purchase a capacity of 40 Gbpsfor TDM, because there are no intermediate amounts of capacity forpurchase. In such a situation, a cable company may purchase asignificant amount of capacity that they may not use, and that couldpotentially cost them more than they are willing to pay to meet theneeds of their customers. Furthermore, with TDM based SONET/SDHnetworks, the time intervals can only be reduced to a certain sizebeyond which it is no longer possible to increase the capacity of aSONET/SDH network. For instance, increasing the capacity of SONET/SDHnetworks to 40 Gbps using TDM technology may prove to be extremelydifficult to achieve in the future.

BRIEF DESCRIPTION OF THE FIGURES

FIG. 1 depicts a schematic of an Optical Communications Module Link(OCML) Extender, in accordance with the disclosure.

FIG. 2 depicts a network architecture, in accordance with thedisclosure.

FIG. 3 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure.

FIG. 4 shows an access link loss budget of a Dense Wave DivisionMultiplexing (DWDM) passive circuit, in accordance with the disclosure.

FIG. 5 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure.

FIG. 6 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure.

FIG. 7 depicts different passive optical network (PON) transceiverparameters associated with downstream transmitting circuits and upstreamtransmitting circuits, in accordance with the disclosure.

FIG. 8 depicts a graphical representation of wavelengths used totransport one or more signals, in accordance with the disclosure.

FIG. 9 a stimulated Raman scattering (SRS) diagram, in accordance withthe disclosure.

FIG. 10 depicts a schematic illustration of wavelength and optical fibermonitoring of cascaded OCML headends in accordance with the disclosure.

FIG. 11 a schematic illustration of wavelength and optical fibermonitoring of an OCML headend in accordance with the disclosure.

FIG. 12 depicts an access network diagram of an OCML headend comprisingwavelength division multiplexers (WDMs), a dense wavelength divisionmultiplexer (DWDM), and optical amplifiers, in accordance with thedisclosure.

FIG. 13 depicts an access network diagram of an OCML headend comprisingWDMs, a DWDM, optical amplifiers, and dispersion control modules (DCMs),in accordance with the disclosure.

FIG. 14 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure.

FIG. 15 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure.

FIG. 16 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure.

FIG. 17A depicts an access network diagram of an OCML headend, inaccordance with the disclosure.

FIG. 17B depicts an access network diagram of amultiplexer-demultiplexer (MDM), in accordance with the disclosure.

FIG. 18 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure.

FIG. 19 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure.

FIG. 20 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure.

FIG. 21 depicts a schematic of an OCML headend according to at least oneembodiment of the disclosure.

FIG. 22 depicts a network diagram of a back-to-back OCML network, inaccordance with the disclosure.

FIG. 23 depicts a network diagram of a back-to-back OCML network, inaccordance with the disclosure.

FIG. 24 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure.

FIG. 25 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure.

DETAILED DESCRIPTION

DWDM passive circuits can be used in combination with one or more otheroptical communications devices to develop novel signal extensioncircuits that increase the range with which light beams are propagatedand the number of signals that can be combined and transmitted from acable company to customers. The circuits disclosed herein may bereferred to Optical Communications Module Link (OCML) Extender. The OCMLpassive circuits, disclosed herein, may increase the capacity ofembedded optical fibers by first assigning incoming optical signals tospecific frequencies (wavelength, denoted by lambda) within a designatedfrequency band and then multiplexing the resulting signals out onto oneoptical fiber. Because incoming signals are never terminated in theoptical layer, the interface can be bit-rate and format independent,thereby allowing the service provider to integrate DWDM passive circuitseasily into a passive circuit, such as an OCML passive circuit, withexisting equipment in the network while gaining access to the untappedcapacity in the embedded optical fibers.

A DWDM passive circuit may combine multiple optical signals fortransportation over a single optical fiber, thereby increasing thecapacity of a service provider's network. Each signal carried can be ata different rate (e.g., optical carrier transmission rate OC-3, OC-12,OC-24, etc.) and in a different format (e.g., SONET, ATM, data, etc.).For example, the networks disclosed herein may comprise DWDM passivecircuits that transmit and receive a mix of SONET signals with differentdata rates (e.g., OC-48 signals with a data rate of 2.5 Gbps or OC-192signals with a data rate of 10 Gbps) can achieve data rates (capacities)of over 40 Gbps. The OCML passive circuits disclosed herein can achievethe aforementioned while maintaining the same degree of systemperformance, reliability, and robustness as current transport systems—oreven surpassing it. The OCML passive circuits may be a smart platform,integrated into a network headend or a network cabinet, and may connecta metro area network that provides internet and telecommunicationsservices to end users (e.g., enterprise multi dwelling unit (MDU)customers, residential customers, commercial customers, and industrialcustomers) via one or more optical fiber links. The OCML passivecircuits may also be referred to as OCML headends. The OCML headend mayenable a plurality of signals to be cost effectively transported overlong optical fiber distances between at least 5 km and 60 km (or anyother distance) without having to put any optical amplifiers or otheractive devices, like an optical switch, (which is normally used toprovide path redundancy in case of an optical fiber cut) in the field.

The OCML headend may be used to transport a mix of multi-wavelengthsignals, which may include, for example, 10GbE, GPON, XGPON/10GEPON, 25GNon-return-to-zero (NRZ), 25G Quasi-Coherent, 25 and/or 50GPulse-Amplitude Modulation (PAM4), 100-600G Coherent, and/or Duo-Binarysignals, over the same optical fiber without having active devices suchas optical amplifiers in the field. These are merely examples of signalsthat may be transported, and any other type of signal may also betransported as well. Throughout the disclosure reference may be made toany individual example signal or a combination of example signals, butany other type of signal could similarly be applicable. The OCML headendmay also be configured to support the same wavelengths over a secondaryoptical fiber via an optical switch in case the primary optical fiberexperiences a cut. In one embodiment, an OCML headend, systems, andmethods may include various subsystems integrated into a single moduleincluding an integrated DWDM passive circuit that combines and separatesbi-directional wavelengths in optical fibers propagating in aconventional wavelength window, such as the c band dispersive region ofthe optical fibers. The OCML headend may comprise a three port or fourport wave division multiplexer (WDM) or circulator to combine andseparate 10GbE downstream and upstream signals of different wavelengths.The OCML headend may also comprise a four port WDM to combine GPON,EPON, and 10GbE optical signals of different wavelengths, whereas theDWDM may combine SONSET/SDH and/or ATM signals. The OCML headend mayalso comprise a five port WDM to combine and separate upstream anddownstream signals comprising GPON, XGPON/10GEPON, and 10GbE opticaldata signals of different wavelengths. Although the term multiplexer isused to describe the WDMs as disclosed herein, the WDMs do notexclusively multiplex (combine) one or more downstream signals into asingle downstream signal, but they also demultiplex (separate) a singleupstream signal into one or more upstream signals.

The WDM may comprise one or more thin film filters (TFFs) or arraywaveguide gratings (AWGs) that combine one or more downstream signalsinto a single downstream signal and separate a single upstream signalinto one or more upstream signals. The WDM may comprise one or morewavelength-converting transponders, wherein each of thewavelength-converting transponders receives an optical data signal(e.g., a 10GbE optical data signal) from a client-layer optical networksuch as, for example, a Synchronous optical network (SONET)/synchronousdigital hierarchy (SDH), Internet protocol (IP), and/or asynchronoustransfer mode (ATM) optical network. Each of the wavelength-convertingtransponders converts the optical data signal into an electrical datasignal, and then converts the electrical data signal into a secondoptical data signal to be emitted by a laser, wherein the second opticaldata signal is carried by one or more packets of light oscillating withwavelengths in the c band. More specifically, each of thewavelength-converting transponders may include a laser that emits thesecond optical data signal. That is each of the second optical datasignals may be emitted by a laser with a unique wavelength. In someembodiments, the wavelength-converting transponders may comprise twoadjacent transceivers. That is, each of the wavelength-convertingtransponders may comprise a first transceiver that converts the opticaldata signal into an electrical data signal, and may comprise secondtransceiver that converts the electrical data signal into the secondoptical data signal. The second transceiver converts the electricalsignal to the second optical data signal such that the second opticaldata signal is transmitted with the correct wavelength.

A first wavelength-converting transponder, of the twowavelength-converting transponders, may emit a second optical datasignal with a 1550 nm wavelength. A second wavelength-convertingtransponder, of the two wavelength-converting transponders, may emit asecond optical data signal with a 1533 nm wavelength. For example, theremay be two wavelength-converting transponders, and each of the twowavelength-converting transponders may include a laser emitting a secondoptical data signal with a unique wavelength. Thus, each of thewavelength-converting transponders converts the electrical data signalinto an optical data signal, and each of the wavelength-convertingtransponders emits, or transmits, the optical data signal, with awavelength in the c band, to a TFF or AWG. The TFF or AWG, may combineor multiplex the optical data signals, emitted by each of thewavelength-converting transponders, into a multi-wavelength optical datasignal wherein each of the wavelengths in the multi-wavelength opticaldata signal coincide with the wavelengths associated with each of theoptical data signals. Returning to the example above of the twowavelength-converting transponders, the first and secondwavelength-converting transponders, may each receive an optical signalfrom a SONET/SDH client layer network. The first and secondwavelength-converting transponders may each respectively convert theoptical signal they received from the SONET/SDH client layer networkinto an electrical data signal. The first wavelength-convertingtransponder may convert the electrical data signal that it receives intoa second optical data signal with a first wavelength. The firstwavelength-converting transponder may emit, via a first laser, thesecond optical data signal, with the first wavelength, to the TFF orAWG. The second wavelength-converting transponder may convert theelectrical data signal that it receives into a second optical datasignal with a second wavelength. The second wavelength-convertingtransponder may emit, via a second laser, the second optical signal,with the second wavelength, to the TFF or AWG. The TFF or AWG maycombine or multiplex the second optical data signal, with the firstwavelength, and the second optical data signal, with the secondwavelength, onto a multi-wavelength optical signal. The TFF or AWG maybe referred to as an optical multiplexer.

The DWDM passive circuits disclosed herein may includewavelength-converting transponders and corresponding WDMs that combineor multiplex optical data signals similar to the WDMs described above.The DWDM passive circuits may also include wavelength-convertingtransponders and corresponding WDMs that separate optical data signals.In some embodiments, the same WDM may combine optical data signals andseparate optical data signals. That is, the WDM may separate one or moreoptical data signals from a multi-wavelength optical data signal, ordemultiplex the one or more optical data signals from themulti-wavelength optical data signal. The WDM may separate the one ormore optical data signals from a multi-wavelength optical data signalusing a process that is the exact opposite of the process used tocombine one or more optical data signals into a multi-wavelength signal.The WDM may separate one or more optical data signals from amulti-wavelength optical data signal that may correspond to an upstreamsignal received from a remote DWDM passive circuit.

The WDM may receive the multi-wavelength optical data signal and one ormore TTF or AWGs may separate the one or more optical data signals, fromthe multi-wavelength optical data signal, using filters or waveguidegratings with properties that separate optical data signals, withdifferent wavelengths, from a multi-wavelength optical data signal.After the WDM has separated the optical data signals, with differentwavelengths, from the multi-wavelength optical data signal, the WDM mayconvert each of the separated optical data signals to a correspondingelectrical data signal. The WDM may then convert the correspondingelectrical data signal to a second optical data signal, wherein thesecond optical data signal may be an optical data signal with signalcharacteristics commensurate for use with a SONET/SDH, IP, or ATMclient-layer optical network.

As mentioned above, the WDM may also be a circulator, or function as acirculator. The circulator may be an optical circulator comprised of afiber-optic component that can be used to separate upstream signals anddownstream signals. The optical circulator may be a three-port orfour-port device (or any other number of ports) in which an optical datasignal entering one port will exit the next port. The optical circulatormay be in the shape of a square, with a first port on the left side ofthe square, a second port on the right side of the square, and a thirdport on the bottom side of the square. A first optical data signal(e.g., a downstream signal) entering the first port may exit the secondport. A second optical data signal (e.g., an upstream signal) enteringthe third port may exit the first port. In some instances, thecirculator may also be round baud. The round baud circulator may allowfor the use of at least 48 total signal channels (e.g., at least 24downstream and 24 upstream channels) of the OCML circuit. The circulatormay a single stage circulator, or may be a dual stage circulator. Thedual stage circulator may have higher isolation. The circulator may bebeneficial in that it allows minimal wavelength separation betweensignals being transmitted. In particular, this may be beneficial withQuasiCoherent and PAM signals, for example.

An upstream signal, as referred to herein, may be a flow one or morepackets of light, oscillating with a predetermined wavelength, along oneor more optical fibers in a direction toward the OCML headend from afield hub or outside plant. A downstream signal, as referred to herein,may be a flow of one or more packets of light, oscillating with apredetermined wavelength, along one or more optical fibers in adirection away from the OCML headend and toward the field hub or outsideplant. The one or more packets of light may correspond to one or morebits of data. Both downstream and upstream signals propagate along thesame optical fiber, but in opposite directions. In some embodiments, thedownstream and upstream signals may propagate along the same fibersimultaneously using one or more wavelength multiplexing techniques asexplained below. This bidirectional simultaneous communication betweenthe OCML headend and the outside plant may be referred to as a fullduplex connection. Field hub and outside plant may be usedinterchangeably.

In some embodiments, the OCML headend may also comprise one or morebooster optical amplifiers that may amplify downstream and/or upstreamsignals based on the length of a fiber between the OCML headend and theoutside plant. In some instances, a booster optical amplifier may be awide band booster optical amplifier. The booster optical amplifier maybe an Erbium Doped Fiber Amplifier (EDFA). The core of the EDFA may bean erbium-doped optical fiber, which may be a single-mode fiber. Thefiber may be pumped, by a laser, with one or more packets of light in aforward or backward direction (co-directional and coutner-directionalpumping). The one or more packets of light pumped into the fiber, mayhave a wavelength of 980 nm. In some embodiments the wavelength may be1480 nm. As the one or more packets of light are pumped into the fibererbium ions (Er³⁺) may be excited and transition into a state where theions can amplify the one or more packets of light with a wavelengthwithin the 1.55 micrometers range. The EDFA may also comprise two ormore optical isolators. The isolators may prevent light pumped into thefiber that leaves the EDFA from returning to the EDFA or from damagingany other electrical components connected to the EDFA. In someembodiments, the EDFA may comprise fiber couplers and photodetectors tomonitor optical power levels. In other embodiments, the EDFA may furthercomprise pump laser diodes with control electronics and gain flatteningfilters. The EDFA may have the effect of amplifying each of the one ormore optical data signals, while they are combined in a multi-wavelengthoptical data signal, without introducing any effects of gain narrowing.In particular, the EDFA may simultaneously amplify the one or moreoptical data signals, each of which have a different wavelength, withina gain region of the EDFA. A gain of the booster optical amplifier maybe based at least in part on the length of the fiber. In someembodiments, the length of the fiber may at least be between 5 and 60kilometers.

The OCML headend may also comprise one or more optical pre-amplifiersthat may amplify upstream and/or downstream signals. In some instances,an optical pre-amplifier may be a wide band booster optical amplifier.The optical pre-amplifier may also be an EDFA. The optical pre-amplifiermay amplify upstream signals based on the length of the fiber betweenthe outside plant and the OCML headend to account for any loses in thestrength of the upstream signals propagating along the fiber. The gainof the optical pre-amplifier may be based at least in part on a requiredsignal strength of the upstream signals at an input to the DWDM passivecircuit, in order for the DWDM to demultiplex the upstream signals. Theoptical pre-amplifier may have the effect of amplifying amulti-wavelength optical data signal, so that the one or more opticaldata signals in the multi-wavelength optical data signal, each of whichhave different respective wavelengths, have a certain received powerlevel at a DWDM passive circuit upstream input port.

The optical signal to noise ratio (OSNR) of the EDFA may be based atleast in part on an input power to the EDFA, a noise figure. In someembodiments the OSNR of the EDFA may be determined by the expressionOSNR=58 dB−NF−P_(in), where NF is the noise floor, P_(in) is the inputpower to the EDFA. 58 dB is constant that is based on Planck's constant,the speed of light, the bandwidth of the EDFA, and the wavelength of theone or more packets of light. In some embodiments, the OSNR of the EDFAsdisclosed herein may be as high as 40 dB, for one or more packets oflight that are transmitted downstream from OCML headend. The OSNR of thetransceivers disclosed herein may be as low as 23 dB, and there may be aplurality of bit error rate (BER) values associated with this 23 dBOSNR. The BER may be determined based at least in part on the energydetected per bit, noise power spectral density, and a complementaryerror function. More specifically the BER may be

${\frac{1}{2}{erf}\;{c\left( \sqrt{\frac{E_{b}}{N_{0}}} \right)}},$wherein E_(b) is the energy detected per bit, N₀ is the noise powerspectral density, and erfc is the complementary error function. Forinstance, the transceivers disclosed herein may be able to achieve a BERof 10⁻¹² when the common logarithm ratio of received power to 1milliwatt (mW) is −23 dBm. For example, a transceiver in the OCMLheadend may receive an upstream flow or one or more packets of light,from a transceiver in the field hub or outside plant, that has a commonlogarithm ratio of received power per mW of −23 dBm. The BER may begreater for common logarithm ratios of received power per mW, meaningthat the BER may decrease with the higher common logarithm ratios ofreceived power per mW. The transceivers may be configured to havegreater OSNRs, and therefore lower BERs for the same value of a commonlogarithm ratio of received power per mW. For example, a firsttransceiver configured to have an OSNR of 24 dB with a common logarithmratio of received power per mW of −28 dBm may have an approximate BER of10⁻⁵ and a second transceiver configured to have an OSNR of 26 dB with acommon logarithm ratio of received power per mW of −28 dBm may have anapproximate BER of 10⁻⁷. Thus, transceivers configured to have a higherOSNR results in the transceiver having a lower BER for the same commonlogarithm ratio of received power per mW. Both the booster opticalamplifier and the optical pre-amplifier, as well as any other amplifiersdescribed herein, may allow operation over a full transmission spectrum,which may include at least 48 transmission channels (at 100 GHz spacing)or 96 transmission channels at 50 GHz spacing

The OCML headend may also comprise an optical switch that may connect aWDM, and/or any other element of the OCML circuit, to a primary opticalfiber, which effectively may connect the OCML passive circuit to theoutside plant. The optical switch may also connect the WDM, and/or anyother element of the OCML circuit, to a secondary optical fiberconnecting the OCML passive circuit to the outside plant. The opticalswitch may be in a first position that connects the WDM to the primaryoptical fiber, and may be in a second position that connects the WDM tothe secondary optical fiber. The optical switch may be in the secondposition when the primary optical fiber is disconnected or unresponsive.Any number of additional optical fibers may be connected to the opticalswitch as well.

Because the OCML headend, field hub or outside plant, and fiberconnecting the OCML headend and field hub or outside plant mainlycomprise passive optical components, in comparison to other optical ringnetworks that primarily have active components, one or more devices maybe needed to control for dispersion of light as it goes throughdifferent optical components. In particular, as packets of lighttraverse the different optical components in the OCML headend (e.g.,WDMs and/or optical amplifiers including booster amplifiers orpre-optical amplifiers), an optical data signal being carried by thepackets of light may begin to experience temporal broadening which is aform of optical data signal distortion. Because the OCML systemsdisclosed herein transmit high data rate optical data signals, which mayinclude at least hundreds of Gbps, there may be dispersive temporalbroadening effects introduced by one or more of the optical componentsin the OCML headend. The optical data signals disclosed herein may carrydigital symbols, which may include a series of binary digits (1 or 0),and each binary digit may be represented by a pulse of light (one ormore packets of light) of a certain amplitude, that lasts a certainperiod. For example, an optical data signal may be carrying a pluralityof digital symbols, wherein a pulse of light that has a certainamplitude and certain pulse width (certain period) represents eachbinary digit in a digital symbol of the plurality of digital symbols.The pulse widths of each of the pulses of light may begin to broaden aseach of the pulses of light traverses different optical components. As aresult, the symbol may begin to broaden. Consequently, each of thesymbols begins to broaden over time, and may become indistinguishablefrom an adjacent symbol. This may be referred to as intersymbolinterference (ISI), and can make it difficult for a fiber-optic sensoror photodetector receiving the optical data signal to distinguishadjacent symbols from one another.

In order to compensate for this phenomenon, one or more dispersioncompensation modules (DCMs) may be inserted between one or more opticalcomponents in the OCML headend. For example, a DCM may be receive anoptical data signal output from a circulator and/or any other element ofthe OCML circuit to compensate for any potential ISI that may beintroduced as a result of different optical data signals, carried overpulses of light, that have been combined, multiplexed, or circulated inthe circulator, or any other element of the OCML circuit. The DCM canalso compensate for dispersion characteristics of the fiber between theOCML headend and the field hub or outside plant. In particular, thefiber may comprise certain optical elements or material impurities thatcan be compensated for in the DCM, wherein the DCM comprises long piecesof dispersion-shifted fibers or chirped fiber Bragg gratings. Thedispersion-shifted fibers or chirped fiber Bragg gratings can reduce ISIthat is introduced by the fiber. In some embodiments, the OCML headendmay comprise one or more DCMs to compensate for ISI that may beintroduced by one or more optical components in the OCML headend orfiber that is either upstream or downstream from the one or more DCMs.For example, in one embodiment, a first DCM may be positioned downstreamfrom a first WDM and a second DCM may be positioned upstream from asecond DCM. Additionally, the DCMs may be tunable. That is, the DCMs canbe tuned based on the transmission distance of a signal. For example, ifa signal is being transmitted over a 60 km fiber, the tunable DCM wouldbe tuned differently than if the signal were being transmitted over a 5km fiber. It should be noted that the DCMs may cause negative dispersionfor shorter lengths of fiber (e.g., lengths of fiber less than 5kilometers). Negative dispersion may occur when a flow of one or morepackets of light, forming a wave, propagate along a distance of thefiber with a negative rate of change. The wave propagates along thefiber, and the wave has an electric field associated with it that isnormal to the direction of propagation of the wave, and a magnetic fieldassociated with it that is normal to the electric field and thedirection of propagation of the wave. The wave propagates along thefiber with an angular frequency, ω, which may be a function of apropagation constant β. The electric and magnetic fields may bothoscillate in accordance with sinusoidal function e^(i(βz−ωt)), wherein zis a distance that the wave has traveled in the fiber, and t is the timeelapsed after the wave has been transmitted by the DCM. That is theelectric and magnetic field may oscillate in accordance with asinusoidal function equal to cos(βz−ωt)+i sin(βz−ωt), wherein theoscillation of the wave is based at least in part on the propagationconstant, and angular frequency, and the amount of time that has elapsedsince the wave has been transmitted by the DCM. The angular frequencymay be reciprocal of the amount of time that the electric and magneticfields oscillate an entire cycle or period. The propagation constant maybe a complex quantity, wherein the real part of the propagation constantis a measure of a change in the attenuation of the wave as it propagatesalong the fiber. The real part of the propagation constant may bereferred to as an attenuation constant. The imaginary part of thepropagation constant is a measure of a change in the phase of the waveas it propagates along the fiber. Because the angular frequency may bebased at least in part on the propagation constant, the angularfrequency of the wave may change as the attenuation and phase of thewave change. Accordingly, the velocity of the wave may change as itpropagates along the fiber and may begin to experience dispersion. Thevelocity of the wave may be the rate at which the angular frequencychanges as the propagation constant changes while the wave propagatesalong the fiber. That is the velocity of the wave may be expressed as

${v = \frac{d\omega}{d\beta}}.$The wavelength of the wave may be expressed as

${\lambda = {2\pi\frac{c}{\omega}}},$wherein c is the speed of light. The dispersion of the wave may be basedat least in part on the speed of light, wavelength of the wave, velocityof the wave, and the rate of change of the velocity of the wave withrespect to the angular frequency. The dispersion of the wave may beexpressed as

$D = {\frac{2\pi\; c}{v^{2}\lambda^{2}}{\frac{dv}{d\;\omega}.}}$D is a dispersion parameter of the wave and is based on the speed oflight (c), the velocity of the wave (v), the wavelength of the wave (λ),and the rate of change or first derivative of the velocity of the wavewith respect to the angular frequency of the wave

$\left( \frac{dv}{d\omega} \right).$The dispersion parameter indicates whether the wave experiences positivedispersion (temporal broadening) or negative dispersion (temporalcontraction) as the wave propagates along the fiber. Negative dispersionmay occur when the rate of change or derivative of the velocity of thewave, with respect to the angular frequency is negative. When

$\left( \frac{dv}{d\omega} \right)$is negative, the wave is said to be experiencing negative dispersion.Thus when the rate of change of the velocity of the wave with respect tothe angular frequency is negative, the wave may experience temporalcontraction. Accordingly, transceivers in the transponders of the DWDMof the field hub or outside plant must be capable of detecting wavessubject to negative dispersion. Negative dispersion is the opposite ofpositive dispersion in that ISI may not occur when a wave is detected atthe transceivers in the transponders of the DWDM of the field hub oroutside plant. However, temporal contraction of the wave may make itdifficult for a fiber-optic sensor or photodetector to detect an opticaldata signal carrying digital symbols, because the digital symbols in theoptical data signal may begin to overlap with one another. This mayhappen because each of the digital symbols are a series of binarydigits, and the binary digits are represented by a pulse of light (oneor more packets of light in the wave), and as the wave begins toexperience negative dispersion, each of the binary digits may begin tooverlap with one another. The transceivers disclosed herein are equippedwith fiber-optic sensors or photodetectors that are capable of correctlydetecting the one or more packets of light in the wave, when the wave issubject to positive and/or negative dispersion. The DCMs disclosedherein may transmit a signal a distance of at least 60 kilometers.

The OCML headend may also comprise a non-optical switch that switchesdue to a loss of light or on demand.

The OCML headend may also comprise wavelength-monitoring ports thatconnect to the primary and secondary optical fibers to monitor thewavelength of upstream signals comprising 10GbE, GPON, XGPON/10GEPON,25G Non-return-to-zero (NRZ), 25G Quasi-Coherent, 25 and/or 50GPulse-Amplitude Modulation (PAM4), 100-600G Coherent, and/or Duo-Binarysignals (and/or any other type of signal) and/or to monitor thewavelength of downstream signals comprising 10GbE, GPON, and/orXGPON/10GEPON, 25G Non-return-to-zero (NRZ), 25G Quasi-Coherent, 25and/or 50G Pulse-Amplitude Modulation (PAM4), 100-600G Coherent, and/orDuo-Binary signals (and/or any other type of signal).

Certain embodiments of the disclosure are directed to an OCML, systems,and methods. Embodiments of the disclosure now will be described morefully hereinafter with reference to the accompanying drawings, in whichcertain embodiments are shown. This disclosure may, however, be embodiedin many different forms and should not be construed as limited to theembodiments set forth herein; rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the disclosure to those skilled in the art. Likenumbers refer to like elements throughout.

It should be noted that the OCML headend may also be referred to as aterminal or Master Terminal Center (MTC). Throughout this disclosurereference may be made to a “Master Terminal Center” or “MTC” forsimplicity, but these term could also be replaced by any other type ofheadend or central hub location in a network. In some embodiments, theOCML headend may be collocated within the MTC. In other embodiments, theOCML headend may be located at a secondary hub, e.g., a secondarytransport center (STC) that may be connected to the MTC via a network.As with the MTC, throughout this disclosure reference may be made to a“secondary transport center” or “STC” for simplicity, but these termcould also be replaced by any other type of secondary hub location in anetwork. In some embodiments, an outside plant may also be referred toas a field hub or remote physical device (RPD). In some embodiments, theoutside plant may be collocated with the RPD. In other embodiments, theoutside plant and RPD may not be collocated and connected via a 10Gigabit transceiver. The outside plant may comprise one or more passiveoptical network devices.

FIG. 1 shows a schematic of an OCML headend according to at least oneembodiment of the disclosure. As shown in FIG. 1, headend 101 is a smartintegrated OCML headend, which is a circuit, comprising one or moreEDFAs (e.g., Optical amplifiers 102 and 104), a DWDM (e.g., DWDM 106),one or more WDMs (e.g., WDM 108 and 110), one or more DCMs (e.g., DCM112 and 114), and an optical switch 116 to feed a primary optical fiber(e.g., Primary Fiber 176) or secondary (backup) optical fiber (e.g.,Secondary Fiber 174). The disclosure provides a method of transportingmultiple 10GbE and GPON/XGPON/10GEPON signals on the same optical fiberover extended links of up to 60 kms without a cable company having toput optical amplifiers between the cable's MTC facility and a field hubor outside plant. The MTC facility may be an inside plant facility wherea cable company acquires and combines services to be offered tocustomers. The MTC facility provides these combined services tocustomers, by transmitting and receiving optical signals over aplurality of optical fibers to a field hub or outside plant whichconnects the plurality of optical fibers to a customer's premise. TheOCML headend may be located in a secondary terminal center (STC) thatconnects the MTC facility to a field hub or outside plant housing amultiplexer-demultiplexer (MDM) (e.g., MDM 208 in FIG. 2).

In one aspect, headend 101 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 190) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 188). 20×10GbE DS 190 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 188 mayreceive upstream data over 10GbE wavelengths. Headend 101 may comprisetwo PON 124 connectors, one of which may be a GPON connector (e.g., GPON184) and one of which may be an XGPON/10GEPON connector (e.g.,XGPON/10GEPON 182). Headend 101 may also comprise twowavelength-monitoring ports (e.g., wavelength-monitoring ports 126), aprimary optical fiber (e.g., primary optical fiber 176) and a secondaryoptical fiber (e.g., secondary optical fiber 174) that transmit andreceive a plurality of multi-wavelength 10GbE and GPON/XGPON/10GEPONoptical signals. Primary optical fiber 176 and secondary optical fiber174 may transmit a first plurality of multi-wavelength 10GbE, GPON,and/or XGPON/10GEPON optical signals from headend 101 to a outside plant(not illustrated in FIG. 1), and may receive a second plurality ofmulti-wavelength 10GbE, GPON, and/or XGPON/10GEPON optical signals fromthe outside plant.

In some embodiments, 20×10GbE DS 190 and 20×10GbE UP 188 may compriseconnectors belonging to the laser shock hardening (LSH) family ofconnectors designed to transmit and receive optical data signals betweenDWDM 106, and one or more cable company servers (not shown). In otherembodiments, 20×10GbE DS 190 and 20×10GbE UP 188 may also comprise E2000connectors, and may utilize a 1.25 millimeter (mm) ferrule. 20×10GbE DS190 and 20×10GbE UP 188 may be installed with a snap-in and push-pulllatching mechanism, and may include a spring-loaded shutter whichprotects the ferrule from dust and scratches. The shutter closesautomatically once the connector is disengaged, locking out impurities,which could later result in network failure, and locking in possiblydamaging lasers. 20×10GbE DS 190 and 20×10GbE UP 188 may operate in asingle mode or a multimode.

In single mode, 20×10GbE DS 190 and 20×10GbE UP 188 only one mode oflight may be allowed to propagate. Because of this, the number of lightreflections created as the light passes through the core of single mode20×10GbE DS 190 and 20×10GbE UP 188 decreases, thereby loweringattenuation and creating the ability for the optical data signal totravel further. Single mode may be for use in long distance, higherbandwidth connections between one or more cable company servers and DWDM106.

In multimode, 20×10GbE DS 190 and 20×10GbE UP 188, may have a largediameter core that allows multiple modes of light to propagate. Becauseof this, the number of light reflections created as the light passesthrough the core increase, creating the ability for more data to passthrough at a given time. Multimode 20×10GbE DS 190 and 20×10GbE UP 188,may generate high dispersion and a attenuation rate, which may reducethe quality of an optical data signal transmitted over longer distances.Therefore multimode may be used to transmit optical data signals overshorter distances.

In one aspect, headend 101 can transmit and receive up to twentybi-directional 10GbE optical data signals, but the actual number ofoptical data signals may depend on operational needs. That is, headend101 can transport more or less than twenty 10GbE downstream opticalsignals, or more or less than twenty 10GbE upstream optical datasignals, based on the needs of customers' networks (e.g., Remote PHYNetwork 216, Enterprise Network 218, Millimeter Wave Network 214). Thesecustomer networks may be connected to headend 101 through an opticalring network (e.g., metro access optical ring network 206).

The operation of headend 101 may be described by way of the processingof downstream optical data signals transmitted from headend 101 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. Each of thetransponders of 20×10GbE DS 190 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 190 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 190 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 106 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 98) comprising the twenty correspondingsecond optical data signals onto a fiber. More specifically, DWDM 106may multiplex the twenty corresponding second optical data signals ontothe fiber, wherein the twenty multiplexed corresponding second opticaldata signals compose the multi-wavelength downstream optical datasignal. The multi-wavelength downstream optical data signal may have awavelength comprising the twenty wavelengths of the twenty correspondingsecond optical data signals.

The multi-wavelength downstream optical data signal 10GbE DS 198, may beinput to a WDM (e.g. WDM 108). WDM 108 may be a three port wave divisionmultiplexer (WDM), or a three port circulator, that receives 10GbE DS198 on port 194 and outputs 10GbE DS 198 on port 186 as 10GbE DS 172.10GbE DS 172 may be substantially the same as 10GbE DS 198 because WDM108 may function as a circulator when 10GbE DS 172 is input on port 194.

10GbE DS 172 may be input into a DCM (e.g., DCM 112) to compensate fordispersion that 10GbE DS 172 may experience after being amplified by anEDFA and multiplexed by a WDM, with other optical data signals, that aredownstream from the DCM. The amplified and multiplexed optical datasignal may be referred to as an egress optical data signal, as it is theoptical data signal that may be transmitted out of headend 101 over afiber connecting headend 101 to a field hub or outside plant. In someembodiments, DCM 112 may be configured to balance positive and/ornegative dispersion that may be introduced to the egress optical datasignal by the fiber. In some embodiments, DCM 112 may be configured tocompensate for positive (temporal broadening of the egress optical datasignal) and/or negative (temporal contraction of the egress optical datasignal) dispersion introduced by fiber that is 80 km or greater inlength, to reduce the sensitivity or OSNR levels of a transceiver in aDWDM located at a field hub or outside plant. More specifically, DCM 112may be configured to reduce the sensitivity or OSNR level requirement ina photodetector or fiber-optic sensor in the transceiver, which maydrastically reduce the cost of the transceivers used in the DWDM locatedat the field hub or outside plant.

DCM 112 may input 10GbE DS 172 and may output 10GbE DS 170 to an EDFA(e.g., booster optical amplifier 102). A gain of the booster opticalamplifier (e.g., booster optical amplifier 102) may be based at least inpart on a distance that a downstream signal has to travel. For example,the gain may be a function of a fiber attenuation coefficient α, whichis a measure of the intensity of the attenuation of a beam of light asit traverses a length of an optical fiber segment. The unit ofmeasurement of the fiber attenuation coefficient is decibels (dB) per km(dB/km). For instance, the gain of booster optical amplifier 102 may beadjusted based at least in part on the attenuation coefficient andlength of fiber that the egress optical data signal will travel. Morespecifically, the gain of booster optical amplifier 102 may beG=e^((2αL)), where α is the fiber attenuation coefficient, as explainedabove, and L is the length of the fiber (e.g., the length of primaryfiber 176 and/or the length of secondary fiber 174). 10GbE DS 170 may beamplified by booster optical amplifier 102, and booster opticalamplifier 102 may output 10GbE DS 178 to port 164 of WDM 110.

WDM 110 may be a WDM that may multiplex 10GbE DS 178 with one or morePON signals (e.g., XGPON/10GEPON 182 and GPON 184). 10GbE DS 178 may bea multi-wavelength optical data signal, wherein the wavelengths comprisethe same wavelengths as 10GbE DS 198. In some embodiments, thewavelengths of the multi-wavelength optical data signal 10GbE DS 178 maybe within the conventional c band of wavelengths, which may includewavelengths within the 1520 nm-1565 nm range. XGPON/10GEPON 182 may be afiber carrying an XGPON/10GEPON optical data signal with a wavelengthwithin the 1571 nm-1582 nm range. GPON 184 may be a fiber carrying aGPON optical data signal with a wavelength of 1490 nm. The XGPON/10GEPONoptical signal may be input to WDM 110 on port 162 and the GPON signalmay be input to WDM 110 on port 160. WDM 110 outputs an egress opticaldata signal from port 156, which may be a multi-wavelength optical datasignal comprising 10GbE, signals. WDM 110 may multiplex 10GbE DS 178,the XGPON/10GEPON optical data signal, and GPON optical data signal thesame way DWDM 106 multiplexes optical data signals. The egress opticaldata signal (e.g., egress optical data signal 152) may be output on port158 of WDM 110 and optical switch 116 may switch egress optical datasignal 152 out of connector 118 or connector 150. In some embodiments,connector 118 may be a primary connector and connector 150 may be asecondary connector or a backup connector. Wavelength monitoringconnector 146 may connect connector 118 to a first port ofwavelength-monitoring ports 126, and wavelength monitoring connector 148may connect connector 150 to a second port of wavelength-monitoringports 126. Wavelength-monitoring ports 126 may monitor the wavelengthsin egress optical data signal 152 via connector 146 or connector 148depending on the position of switch 116. Egress optical data signal 152may exit headend 101 either via connector 144 connected to primary fiber176 or via connector 142 connected to secondary fiber 174 depending onthe position of switch 116. Egress optical data signal 152 may betransmitted on primary fiber 176 to a first connector in the field hubor outside plant, or may be transmitted on secondary fiber 174 to asecond connector in the field hub or outside plant. The field hub oroutside plant may include a MDM with the first connector and the secondconnector.

The operation of headend 101 may be described by way of the processingof upstream optical data signals received at headend 101 from a fieldhub or outside plant. For instance, a multi-wavelength ingress opticaldata signal, comprising one or more of a 10GbE optical data signal,XGPON/10GEPON optical data signal, and/or GPON optical data signal, maybe an upstream optical data signal received on primary fiber 176 orsecondary fiber 174 depending on the position of switch 116. Because themulti-wavelength ingress optical data signal is routed to port 158 ofWDM 110, and is altered negligibly between connector 144 and port 158 orconnector 142 and port 158, depending on the position of switch 116, themulti-wavelength ingress optical data signal may be substantially thesame as ingress optical data signal 154. The multi-wavelength ingressoptical data signal may traverse connector 118 and switch 116, beforeentering WDM 110 via port 158 if switch 116 is connected to connector118. The multi-wavelength ingress optical data signal may traverseconnector 150 switch 116, before entering WDM 110 via port 158 if switch116 is connected to connector 150. WDM 110 may demultiplex one or more10GbE optical data signals, XGPON/10GEPON optical data signals, and/orGPON optical data signals from ingress optical data signal 154. WDM 110may transmit the one or more XGPON/10GEPON optical data signals alongXGPON/10GEPON 182 to one of PON connectors 124 via port 162. WDM 110 maytransmit the one or more GPON optical data signals along GPON 184 to oneof PON connectors 124 via port 160. WDM 110 may transmit the one or more10GbE optical data signals (e.g., 10 GbE UP 180) out of port 156 to DCM114.

In some embodiments, DCM 114 may be configured to balance positiveand/or negative dispersion that may be introduced to a SONET/SDH egressoptical data signal that may exit headend 101 from 20×10GbE UP 188. TheSONET/SDH egress optical data signal may be an upstream signal from afield hub or outside plant destined for a MTC. For example, a customerpremise may be connected to the field hub or outside plant and may sendone or more packets via a SONET/SDH network to the field hub or outsideplant which may in turn transmit the one or more packets using 10GbEoptical data signals to headend 101. The one or more packets may bedestined for a company web server connected to the MTC via a backbonenetwork. Because headend 101 may be collocated in a STC that isconnected to the MTC via an optical ring network, wherein the connectionbetween the STC and MTC is an SONET/SDH optical network connection, DCM114 may be configured to compensate for positive and/or negativedispersion on the SONET/SDH optical network connection. That is DCM 114may be configured to reduce temporal broadening of the SONET/SDH ingressoptical data signal or temporal contraction of the SONET/SDH ingressoptical data signal. DCM 114 may input 10GbE UP 180 and may output 10GbEUP 166 to an input of EDFA (e.g., optical pre-amplifier 104).

A gain of optical pre-amplifier 104 may be based at least in part on adistance that the SONET/SDH egress optical data signal has to travel.For example, the gain may be a function of a fiber attenuationcoefficient α, which is a measure of the intensity of the attenuation ofa beam of light as it traverses a length of an optical fiber segment onthe SONET/SDH optical network connection. For instance, the gain ofoptical pre-amplifier 104 may be adjusted based at least in part on theattenuation coefficient and length of fiber that the egress optical datasignal will travel. More specifically, the gain of optical pre-amplifier104 may be G=e^((2αL)), where α is the fiber attenuation coefficient, asexplained above, and L is the length of the fiber (e.g., the length ofthe fiber of the SONET/SDH optical network connection). 10GbE UP 166 maybe amplified by optical pre-amplifier 104, and optical pre-amplifier 104may output 10GbE UP 168 to WDM 108.

The wavelength of 10GbE UP 168 may be within the conventional c band ofwavelengths, which may include wavelengths within the 1520 nm-1565 nmrange. The one or more XGPON/10GEPON optical data signals may have awavelength within the 1571 nm-1582 nm range, and the one or more GPONoptical data signals may have a wavelength of 1490 nm.

WDM 108 may receive 10GbE UP 168 on port 192, and may output 10GbE UP168 on port 194 as a multi-wavelength upstream optical data signal(e.g., 10GbE UP 196). 10GbE UP 196 is substantially the same as 10GbE UP168 because WDM 108 may function as a circulator when 10GbE UP 168 isinput to port 192. 10GbE UP 196 may be received by DWDM 106, and DWDMmay demultiplex one or more 10GbE optical data signals from 10GbE UP196. Because 10GbE UP 196 is a dispersion compensated amplified versionof the multi-wavelength ingress optical data signal, DWDM 106 maydemultiplex the one or more optical data signals into individual opticaldata signals in accordance with the individual wavelengths of any 10GbEoptical data signals in the multi-wavelength ingress optical datasignal. More specifically, 10GbE UP 196 may be demultiplexed into twenty10GbE optical data signals, each of which may have a unique wavelength.DWDM 106 may output each of the twenty 10GbE optical data signals toeach of the transponders of 20×10GbE UP 188. Each of the transponders of20×10GbE UP 188 may convert a received corresponding 10GbE optical datasignal, of the 10GbE optical data signals, into a correspondingelectrical signal. More specifically, a first transceiver in each of thetransponders may convert each of the twenty 10GbE optical data signalsinto the corresponding electrical signal. Each of the transponders mayalso comprise a second transceiver that may convert the correspondingelectrical signal into a SONET/SDH optical data signal with acorresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 188 may transmit thetwenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

FIG. 2 depicts an network architecture, in accordance with thedisclosure. The network architecture may comprise a MTC Master TerminalFacility (for example MTC Master Terminal Facility 201) that may connecta cable company to the Internet through a backbone network (for exampleBackbone Network 202). MTC Master Terminal Facility 201 may include oneor more servers hosting content that may be consumed by customer devicesconnected to the one or more servers via one or more networks. Forexample, the one or more networks may include cellular or millimeterwave networks (for example Millimeter Wave Network 214), remote physicalnetworks (for example Remote PHY Network 216), enterprise networks (forexample Enterprise Network 218), and one or more passive opticalnetworks (PON) (for example PON 222 and PON 242). MTC Master TerminalFacility 201 may be connected to these one or more networks via one ormore optical fibers (for example Primary Optical Fiber 211 and SecondaryOptical Fiber 213). MTC Master Terminal Facility 201 may connect to theone or more optical fibers via an OCML terminal (for example, OCMLterminal 207), and the one or more networks may connect to the one ormore optical fibers via a MDM (for example MDM 208) comprisingmultiplexer-demultiplexer (for example DMux 288), and PON port (forexample PON 298). OCML 207, Primary Optical Fiber 211, Secondary OpticalFiber 213, and MDM 208 form a network that may be referred to as theMetro Access Optical Ring Network (for example Metro Access Optical RingNetwork 206). DMux 288 may multiplex optical data signals received fromthe one or more networks and transmit the multiplexed optical datasignals to OCML 207. Conversely DMux 288 may demultiplex optical datasignals received from OCML 207 and transmit the demultiplexed opticaldata signals to the one or more networks. Millimeter Wave Network 214may be connected to DMux 288 via connection 254. Remote PHY Network 216may be connected to DMux 288 via connection 256. Enterprise Network 218may be connected to DMux 288 via connection 258. PON 222 may beconnected to DMux 288 via connection 251. PON 242 however may beconnected to PON 298 via connection 253.

Millimeter Wave Network 214 may comprise one or more cellular or Wi-Fimasts with one or more modems (for example Modem 212) that providemobile devices (for example devices 215) with access to content hostedby the one or more servers at MTC Master Terminal Facility 201.

Remote PHY Network 216 may comprise one a remote physical (PHY) node(for example Remote PHY Node 207) that may comprise an opticalcommunications interface that connects to connection 256 and a cableinterface that connects to one or more cable devices (for exampledevices 217) via cables 226-cable 236. The one or more cable devices maybe devices connecting cable set-top boxes in one or more residential,commercial, or industrial buildings to a tap at devices 217.

Enterprise Network 218 may comprise one or more offices requiringhigh-speed access to the Internet via Backbone Network 202 for example.Enterprise Network 218 may connect to the Internet via connection 258.

PON 222 may comprise one or more PON devices (for example devices 299)that require access to MTC Master Terminal Facility 201 or the Internetvia for Backbone Network 202 for example. Devices 299 may be connectedto a splitter (for example Splitter 223) via connections 225-connection227. Splitter 223 is an optical splitter that may combine one or moreoptical data signals from each of devices 299 and transmit them toStrand PON optical line terminal (OLT) 210 via connection 252. Splitter223 may also separate one or more optical data signals received fromStrand PON LOT 210 via connection 252 into one or more optical datasignals for each of devices 299. Strand PON OLT 210 may be an OLT thatconnects optical network units (ONUs) at a customer premises to DMux288. Because one or more optical data signals can be transmitted as amultiplexed signal on a single strand of fiber, Strand PON OLT 210 maybe connected to other PONs (not shown), in addition to PON 222, and maycombine optical data signals received from the PONs and transmit thecombined optical data signals to DMux 288. Strand PON OLT 210 mayseparate optical data signals received from DMux 288 into correspondingoptical data signals each of which is for transmission to acorresponding PON.

PON 242 may comprise one or more PON devices (for example devices 249)that require access to MTC Master Terminal Facility 201 or the Internetvia for Backbone Network 202 for example. Devices 249 may be connectedto a splitter (for example Splitter 243) via connections 224-connection247. Splitter 243 is an optical splitter that may combine one or moreoptical data signals from each of devices 249 and transmit them to PON298 via connection 253. Splitter 243 may also separate one or moreoptical data signals received from PON 298 via connection 253 into oneor more optical data signals for each of devices 249.

FIG. 3 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure. FIG. 3 shows a schematic of anOCML headend according to at least one embodiment of the disclosure. Asshown in FIG. 3, headend 330 is a smart integrated OCML headend, whichis a circuit, comprising a DWDM (e.g., DWDM 307), a WDM (e.g., WDM 305),a GPON port (e.g., GPON PORT 301), an XGPON/10GEPON port (e.g.,XGPON/10GEPON PORT 303), and an optical switch 308 to feed a primaryoptical fiber (e.g., Primary Fiber 309) or secondary (backup) opticalfiber (e.g., Secondary Fiber 311). DWDM 307 may be similar infunctionality to DWDM 106 and WDM 305 may be similar in functionality toWDM 108. The disclosure provides a method of transporting multiple10GbE, GPON, and/or /XGPON/10GEPON signals on the same optical fiberover extended links of up to 60 kms without a cable company having toput optical amplifiers between the cable's Master Terminal Center (MTC)facility and a outside plant (e.g., Outside plant 350). The MTC facilitymay be an inside plant facility where a cable company acquires andcombines services to be offered to customers. The MTC facility providesthese combined services to customers, by transmitting and receivingoptical signals over a plurality of optical fibers to a outside plant orfield hub which connects the plurality of optical fibers to a customer'spremise. The OCML headend may be located in a secondary terminal center(STC) that connects the MTC facility to a field hub or outside planthousing a multiplexer-demultiplexer (MDM) (e.g., MDM 208 in FIG. 2).

In one aspect, headend 330 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 304) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 306). 20×10GbE DS 304 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 306 mayreceive upstream data over 10GbE wavelengths. 20×10GbE DS 304 maycomprise the same elements and perform the same operations as 20×GbE DS190, and 20×10GbE UP 306 may comprise the same elements and perform thesame operations as 20×GbE UP 188.

The operation of headend 330 may be described by way of the processingof downstream optical data signals transmitted from headend 330 to aoutside plant (e.g., Outside plant 350), and the processing of upstreamoptical data signals received from the field hub or outside plant. Eachof the transponders of 20×10GbE DS 304 may receive a SONET/SDH opticaldata signal from a MTC and each of the transponders may convert theSONET/SDH optical data signal into an electrical signal. Morespecifically, a first transceiver in the transponder may convert theSONET/SDH optical data signal into an electrical signal. A secondtransceiver may then convert the electrical signal into a second opticaldata signal, wherein the second optical data signal comprises one ormore packets of light each of which may have a distinct wavelength.Because the one or more packets of light each have a distinctwavelength, the second optical data signal may be said to have thisdistinct wavelength. Thus, the twenty transponders in 20×10GbE DS 304may each receive a SONET/SDH optical data signal, and each of the twentytransponders may convert the received SONET/SDH optical data signal intoa corresponding second optical data signal, wherein each of thecorresponding second optical data signals has a unique wavelength. Thatis, the wavelength of each of the corresponding second optical datasignals is distinguishable from the wavelength of any of the othercorresponding second optical data signals. Thus 20×10GbE DS 304 maygenerate twenty corresponding second optical data signals each of whichhas a unique wavelength.

DWDM 307 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 336) comprising the twenty corresponding secondoptical data signals onto a fiber. The multi-wavelength downstreamoptical data signal 336 may be a 10GbE optical data signal. Morespecifically, DWDM 307 may multiplex the twenty corresponding secondoptical data signals onto the fiber, wherein the twenty multiplexedcorresponding second optical data signals compose the multi-wavelengthdownstream optical data signal. The multi-wavelength optical data signalmay have a wavelength comprising the twenty wavelengths of the twentycorresponding second optical data signals.

The multi-wavelength downstream optical data signal 336, may be input toa WDM (e.g. WDM 305). WDM 305 may be a four port wave divisionmultiplexer (WDM), or a four port circulator, that receivesmulti-wavelength downstream optical data signal 336 on port 321. WDM 305may also receive an XGPON/10GEPON signal, carried on a first fiber(e.g., XGPON/10GEPON 334), on port 302, a GPON signal, carried on asecond fiber (e.g., GPON 332), on port 322, and may multiplexmulti-wavelength downstream optical data signal 336 with theXGPON/10GEPON and GPON signal. XGPON/10GEPON 334 may be a fiber carryingan XGPON/10GEPON optical data signal with a wavelength within the 1571nm-1591 nm and 1260 nm-1280 nm range. GPON 332 may be a fiber carrying aGPON optical data signal with a wavelength of 1490 nm and 1310 nm. WDM305 outputs an egress optical data signal from port 324, which may be amulti-wavelength optical data signal comprising 10GbE, XGPON/10GEPON,and/or GPON optical data signals. WDM 305 may multiplex multi-wavelengthdownstream optical data signal 336, the XGPON/10GEPON optical datasignal, and GPON optical data signal the same way DWDM 307 multiplexesoptical data signals. The egress optical data signal (e.g., egressoptical data signal 338) may be output on port 324 of WDM 305 andoptical switch 308 may switch egress optical data signal 338 ontoprimary fiber 309 or secondary fiber 311 depending on the position ofswitch 308. Egress optical data signal 338 may be transmitted on primaryfiber 309 to a first connector at outside plant 350, or may betransmitted on secondary fiber 311 to a second connector at outsideplant 350. Outside plant 350 may include a MDM with the first connectorand the second connector.

The operation of outside plant 350 may be described by way of theprocessing of a downstream optical data signal received from headend330. Egress optical data signal 338 may be received on the first orsecond connector at outside plant 350 based on a position of opticalswitch 380, as ingress optical data signal 356. That is ingress opticaldata signal 356 may be similar to egress optical data signal 338.Ingress optical data signal 356 may be received by WDM 313 via port 372.WDM 313 may demultiplex ingress optical data signal 356 into amulti-wavelength downstream optical data signal 359, an XGPON/10GEPONoptical data signal that may be output on port 392 onto a first fiber(e.g., XGPON/10GEPON 354), and/or a GPON optical data signal output onport 382 onto a second fiber (e.g., GPON 352). The XGPON/10GEPON opticaldata signal may be received on XGPON/10GEPON port 353 and the GPONoptical data signal may be received on GPON port 351.

The multi-wavelength downstream optical data signal 359 may be output onport 362 and received by DWDM 315 which may be an array waveguidegratings (AWG) or TFF. The multi-wavelength downstream optical datasignal 359 may comprise 10GbE optical data signals. DWDM 315 maydemultiplex the multi-wavelength downstream optical data signal 359 intoindividual optical data signals in accordance with the individualwavelengths of the 10GbE optical data signals. More specifically, themulti-wavelength downstream optical data signal 359 may be demultiplexedinto twenty 10GbE optical data signals, each of which may have a uniquewavelength. DWDM 315 may output each of the twenty 10GbE optical datasignals to each of the transponders of 20×10GbE DS 312. Each of thetransponders of 20×10GbE DS 312 may convert a received corresponding10GbE optical data signal, of the 10GbE optical data signals, into acorresponding electrical signal. More specifically, a first transceiverin each of the transponders may convert each of the twenty 10GbE opticaldata signals into the corresponding electrical signal. Each of thetransponders may also comprise a second transceiver that may convert thecorresponding electrical signal into a SONET/SDH optical data signalwith a corresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. In some embodiments, DWDM 315 may output one or more 10GbEoptical data signals (e.g., RPD DS 327) to a remote physical (PHY)device (RPD) (e.g., RPD 317). RPD 317 may be similar to Remote PHY Node207 in functionality. RPD 317 may convert the one or more 10GbE opticaldata signals into an electrical signal that may be transmitted over oneor more coaxial cables. RPD 317 may also convert one or more electricalsignals into one or more 10GbE optical data signal for transmission to atransponder (e.g., 20×10GbE UP 314).

The operation of outside plant 350 may be further described by way ofthe processing of a uptream optical data signal transmitted to headend330. Each of the transponders of 20×10GbE UP 314 may receive a SONET/SDHoptical data signal from one or more devices providing cable tocustomers or subscribers to a cable's services. For example, the one ormore devices may be any of devices 217, and RPD 327 may be connected todevices 217 via cable 226 . . . cable 236. Cable 226 . . . cable 236 maybe coaxial cables. Each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE UP 314 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE UP 314 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 315 may receive twenty corresponding second optical data signals asan input and output a multi-wavelength downstream optical data signal(e.g., 358) comprising the twenty corresponding second optical datasignals onto a fiber. In some embodiments, RPD 317 may transmit one ormore 10GbE optical data signals (e.g., RPD DS 331) to one or more of20×10GbE UP 314. RPD DS 331 may be 10GbE optical data signals thatgenerated by RPD 317 in response to RPD 317 receiving electrical signalson coaxial cables connecting a remote physical (PHY) network (e.g.,remote PHY network 216) to DWDM 315. The multi-wavelength downstreamoptical data signal 358 may be a 10GbE optical data signal. Morespecifically, DWDM 315 may multiplex the twenty corresponding secondoptical data signals onto the fiber, wherein the twenty multiplexedcorresponding second optical data signals compose the multi-wavelengthdownstream optical data signal. The multi-wavelength optical data signalmay have a wavelength comprising the twenty wavelengths of the twentycorresponding second optical data signals.

The multi-wavelength downstream optical data signal 358, may be input toa WDM (e.g. WDM 313). WDM 313 may be a four port wave divisionmultiplexer (WDM), or a four port circulator, that receivesmulti-wavelength downstream optical data signal 358 on port 362. WDM 313may also receive an XGPON/10GEPON signal, carried on a first fiber(e.g., XGPON/10GEPON 354), on port 392, a GPON signal, carried on asecond fiber (e.g., GPON 352), on port 382, and may multiplexmulti-wavelength downstream optical data signal 358 with theXGPON/10GEPON and GPON signal. XGPON/10GEPON 354 may be a fiber carryingan XGPON/10GEPON optical data signal with a wavelength within the 1571nm-1591 nm and 1260 nm-1280 nm range. GPON 352 may be a fiber carrying aGPON optical data signal with a wavelength of 1490 nm or 1310 nm. WDM313 outputs an egress optical data signal from port 372, which may be amulti-wavelength optical data signal comprising 10GbE, XGPON/10GEPON,and/or GPON optical data signals. WDM 313 may multiplex multi-wavelengthdownstream optical data signal 358, the XGPON/10GEPON optical datasignal, and GPON optical data signal the same way DWDM 307 multiplexesoptical data signals. The egress optical data signal (e.g., egressoptical data signal 357) may be output on port 372 of WDM 313 andoptical switch 380 may switch egress optical data signal 357 ontoprimary fiber 309 or secondary fiber 311 depending on the position ofswitch 380. Egress optical data signal 357 may be transmitted on primaryfiber 309 to a first connector at headend 330, or may be transmitted onsecondary fiber 311 to a second connector at headend 330.

The operation of headend 330 may be further described by way of theprocessing of an upstream optical data signal received from outsideplant 350. Egress optical data signal 357 may be received on the firstor second connector at headend 330 based on a position of optical switch308, as ingress optical data signal 339. That is ingress optical datasignal 339 may be similar to egress optical data signal 357. Ingressoptical data signal 339 may be received by WDM 305 via port 324. WDM 305may demultiplex ingress optical data signal 339 into a multi-wavelengthupstream optical data signal 337, an XGPON/10GEPON optical data signalthat may be output on port 302 onto a first fiber (e.g., XGPON/10GEPON334), and/or a GPON optical data signal output on port 322 onto a secondfiber (e.g., GPON 332). The XGPON/10GEPON optical data signal may bereceived on XGPON/10GEPON port 303 and the GPON optical data signal maybe received on GPON port 301.

The multi-wavelength upstream optical data signal 339 may be output, asmulti-wavelength upstream optical data signal 337, on port 321 andreceived by DWDM 307. The multi-wavelength upstream optical data signal337 may comprise 10GbE optical data signals. DWDM 307 may demultiplexthe multi-wavelength upstream optical data signal 337 into individualoptical data signals in accordance with the individual wavelengths ofthe 10GbE optical data signals. More specifically, the multi-wavelengthupstream optical data signal 337 may be demultiplexed into twenty 10GbEoptical data signals, each of which may have a unique wavelength. DWDM307 may output each of the twenty 10GbE optical data signals to each ofthe transponders of 20×10GbE UP 306. Each of the transponders of20×10GbE UP 306 may convert a received corresponding 10GbE optical datasignal, of the 10GbE optical data signals, into a correspondingelectrical signal. More specifically, a first transceiver in each of thetransponders may convert each of the twenty 10GbE optical data signalsinto the corresponding electrical signal. Each of the transponders mayalso comprise a second transceiver that may convert the correspondingelectrical signal into a SONET/SDH optical data signal with acorresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 306 may transmit thetwenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

FIG. 4 shows an access link loss budget of a Dense Wave DivisionMultiplexing (DWDM) passive circuit, in accordance with the disclosure.Link loss budget 400 illustrates the link loss budget in decibels (dB)associated with a physical optical link connecting an OCML transceiverto a outside plant transceiver. The OCML headend and outside planttransceiver may comprise 10GbE transceivers that may not contribute tothe loss budget. That is there may be no power lost when the 10GbEtransceivers transmit a 10GbE optical data signal. Thus, Txcvr Pwr/WL401 may be equal to 0.0 when a transceiver at an OCML headend transmitsa 10GbE optical data signal to a outside plant transceiver, and when thetransceiver at the outside plant transmits a 10GbE optical data signalto the OCML terminal. The transceiver in the OCML headend may be similarto a transceiver included in the transponders disclosed herein (e.g.,20×10GbE DS 190 or 20×10GbE UP 188 in headend 101 or 20×10GbE DS 304 or20×10GbE UP 306 in OCML headend 301). The transceiver in the outsideplant may be similar to a transceiver included in the transpondersdisclosed herein (e.g., 20×10GbE DS 312 or 20c10GbE UP 314).

In some embodiments, the fiber connecting the transceiver at the OCMLheadend to the outside plant, may be 5 kilometers (km). Thus fiber 402may be 5 km in length and when a transceiver in the OCML headendtransmits an optical data signal (e.g., 10GbE optical data signal) to atransceiver in the outside plant along fiber 402, fiber 402 may causethe optical data signal to experience a 1.25 dB loss. Similarly, whenthe transceiver in the outside plant transmits an optical data signal tothe OCML headend along fiber 402, fiber 402 may cause the optical datasignal to experience a 11.25 dB loss. (How is the 11.5 dB derived? A 60Km fiber would cause 13.2 dB at) 0.22 dB/Km

In some embodiments, a multiplexer in a DWDM (e.g., DWDM 106 or DWDM307) in an OCML headend may contribute to the loss budget. This may bebased at least in part on the multiplexing process applied to multipleinput optical data signals received from multiple transponders (e.g.,20×10GbE DS 190 or 20×10GbE DS 304). The multiplexing process may resultin the multiplexed optical data signal having less power than themultiple input optical data signals. The OCML headend in someembodiments, may also be referred to as the headend, and thus headendDWDM mux 403 is the loss budget associated with the multiplexing ofmultiple input optical data signals. The loss budget for headend DWDMmux 403 may be 5.8 dB. Similarly a demultiplexer in a DWDM in a outsideplant may contribute to the loss budget. This may be based at least inpart on the demultiplexing process applied to a multiplexed optical datasignal received from the DWDM in the headend. The demultiplexing processmay result in each of the demultiplexed optical data signals, includedin the received multiplexed optical data signal, having less power thanthe received multiplexed optical data signal. Thus the loss budget forfield DWDM DeMux 404 may be 5.8 dB.

In some embodiments, an optical switch (e.g., optical switch 116 oroptical switch 308) may contribute to the loss budget experienced by anoptical data signal is transmitted from the OCML headend to the outsideplant or an optical data signal received at the OCML headend from theoutside plant. This may be due to the fact that the optical switch maycomprise one or more electronics that may cause the optical data signalto experience some loss in power as it is it switched from one connectorto another in the OCML headend. Thus switch (headend) 405 may cause theoptical data signal to experience a 1.5 dB loss.

In some embodiments, there may be an optical passive componentconnecting the OCML headend to the outside plant. For instance, theremay be a first fiber connection between the OCML headend and the opticalpassive component, and a second fiber connection between the opticalpassive component and the outside plant. This is depicted as passiveoptical component 625 in FIG. 6 below. The optical passive component,may cause optical data signals transmitted between the OCML headend andthe outside plant to experience some loss in power. The optical passivecomponent may be a 3 dB optical passive component (i.e., 3 dB opticalpassive 406) that may cause the optical data signals to experience a 3.5dB loss.

In some embodiments, there may be two connectors at the OCML headend(e.g., connector 118 and connector 150). Each may cause an optical datasignal sent to a outside plant or received from the outside plant toexperience a loss in power. Each connector may contribute a 0.3 dB lossresulting in the two connectors (connectors 407) contributing a totalloss of 0.6 dB.

In some embodiments, a safety margin (e.g., safety margin 408) of 3 dBmay be included.)

FIG. 5 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure. FIG. 5 shows a schematic of anOCML headend according to at least one embodiment of the disclosure. Asshown in FIG. 5, headend 530 is a smart integrated OCML headend, whichis a circuit, comprising a DWDM (e.g., DWDM 507), a first WDM (e.g., WDM505), a second WDM (e.g., WDM 509), a GPON port (e.g., GPON PORT 501),an XGPON/10GEPON port (e.g., XGPON/10GEPON PORT 503), an EDFA (e.g.,EDFA 541), and an optical switch 508 to feed a primary optical fiber(e.g., Primary Fiber 540) or secondary (backup) optical fiber (e.g.,Secondary Fiber 511). DWDM 507 may be similar in functionality to DWDM106 and WDM 505 and WDM 509 may be similar in functionality to WDM 108.The disclosure provides a method of transporting multiple 10GbE andGPON/XGPON/10GEPON signals on the same optical fiber over extended linksof up to 60 kms without a cable company having to put optical amplifiersbetween the cable's Master Terminal Center (MTC) facility and a outsideplant (e.g., Outside plant 550) or field hub. The MTC facility may be aninside plant facility where a cable company acquires and combinesservices to be offered to customers. The MTC facility provides thesecombined services to customers, by transmitting and receiving opticalsignals over a plurality of optical fibers to a field hub or outsideplant which connects the plurality of optical fibers to a customer'spremise. The OCML headend may be located in a secondary terminal center(STC) that connects the MTC facility to a field hub or outside planthousing a multiplexer-demultiplexer (MDM) (e.g., MDM 208 in FIG. 2).

In one aspect, headend 530 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 504) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 506). 20×10GbE DS 504 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 506 mayreceive upstream data over 10GbE wavelengths. 20×10GbE DS 504 maycomprise the same elements and perform the same operations as 20×GbE DS190, and 20×10GbE UP 506 may comprise the same elements and perform thesame operations as 20×GbE UP 188.

The operation of headend 530 may be described by way of the processingof downstream optical data signals transmitted from headend 530 to aoutside plant (e.g., Outside plant 550), and the processing of upstreamoptical data signals received from the outside plant. Each of thetransponders of 20×10GbE DS 504 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 504 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 504 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 507 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., multi-wavelength downstream optical data signal 547)comprising the twenty corresponding second optical data signals onto afiber. The multi-wavelength downstream optical data signal 547 may be a10GbE optical data signal. More specifically, DWDM 507 may multiplex thetwenty corresponding second optical data signals onto the fiber, whereinthe twenty multiplexed corresponding second optical data signals composethe multi-wavelength downstream optical data signal. Themulti-wavelength optical data signal may have a wavelength comprisingthe twenty wavelengths of the twenty corresponding second optical datasignals.

The multi-wavelength downstream optical data signal 547, may be input toWDM 505. WDM 505 may be a four port wave division multiplexer (WDM), ora four port circulator, that receives multi-wavelength downstreamoptical data signal 547 on port 542. WDM 505 may function as acirculator and may output multi-wavelength downstream optical datasignal 538, on port 540, to WDM 509. Multi-wavelength downstream opticaldata signal 538 may be substantially the same as multi-wavelengthdownstream optical data signal 547. WDM 509 may receive multi-wavelengthdownstream optical data signal 538, and may also receive anXGPON/10GEPON signal, carried on a first fiber (e.g., XGPON/10GEPON534), on port 548, a GPON signal, carried on a second fiber (e.g., GPON532), on port 549, and may multiplex multi-wavelength downstream opticaldata signal 538 with the XGPON/10GEPON and GPON signal. XGPON/10GEPON534 may be a fiber carrying an XGPON/10GEPON optical data signal with awavelength within the 1571 nm-1591 nm and 1260 nm-1280 nm range. GPON532 may be a fiber carrying a GPON optical data signal with a wavelengthof 1490 or 1310 nm. WDM 509 outputs an egress optical data signal fromport 542, which may be a multi-wavelength optical data signal comprising10GbE, XGPON/10GEPON, and/or GPON optical data signals. WDM 509 maymultiplex multi-wavelength downstream optical data signal 538, theXGPON/10GEPON optical data signal, and GPON optical data signal the sameway DWDM 307 multiplexes optical data signals. The egress optical datasignal (e.g., egress optical data signal 539) may be output on port 542of WDM 509 and optical switch 508 may switch egress optical data signal539 onto primary fiber 540 or secondary fiber 511 depending on theposition of switch 508. Egress optical data signal 539 may betransmitted on primary fiber 540 to a first connector at outside plant550, or may be transmitted on secondary fiber 511 to a second connectorat outside plant 550. Outside plant 550 may include a MDM with the firstconnector and the second connector.

The operation of outside plant 550 may be described by way of theprocessing of a downstream optical data signal received from headend530. Egress optical data signal 539 may be received on the first orsecond connector at outside plant 550 based on a position of opticalswitch 580, as ingress optical data signal 582. That is ingress opticaldata signal 582 may be similar to egress optical data signal 539.Ingress optical data signal 582 may be received by WDM 513 via port 584.WDM 513 may demultiplex ingress optical data signal 582 into amulti-wavelength downstream optical data signal 599, an XGPON/10GEPONoptical data signal that may be output on port 595 onto a first fiber(e.g., XGPON/10GEPON 554), and/or a GPON optical data signal output onport 596 onto a second fiber (e.g., GPON 552). The XGPON/10GEPON opticaldata signal may be received on XGPON/10GEPON port 553 and the GPONoptical data signal may be received on GPON port 551.

The multi-wavelength downstream optical data signal 599 may be output onport 597 and received by EDFA 544. The multi-wavelength downstreamoptical data signal 559 may comprise 10GbE optical data signals. A gainassociated EDFA 544 may be based at least in part on a distance that10GbE optical data signals have to travel. For example, the gain may bea function of a fiber attenuation coefficient α, which is a measure ofthe intensity of the attenuation of a beam of light as it traverses alength of an optical fiber segment. The unit of measurement of the fiberattenuation coefficient is decibels (dB) per km (dB/km). For instance,the gain of booster optical amplifier 544 may be adjusted based at leastin part on the attenuation coefficient and length of fiber that theegress optical data signal will travel. More specifically, the gain ofbooster optical amplifier 544 may be G=e^((2αL)), where α is the fiberattenuation coefficient, as explained above, and L is the length of thefiber (e.g., the length of primary fiber 540 and/or the length ofsecondary fiber 511). Multi-wavelength upstream optical data signal 599may be amplified by EDFA 544, and EDFA 544 may output multi-wavelengthdownstream optical data signal 598 to DWDM 515.

DWDM 515 may demultiplex the multi-wavelength downstream optical datasignal 589 into individual optical data signals in accordance with theindividual wavelengths of the 10GbE optical data signals. Morespecifically, the multi-wavelength downstream optical data signal 598may be demultiplexed into twenty 10GbE optical data signals, each ofwhich may have a unique wavelength. DWDM 515 may output each of thetwenty 10GbE optical data signals to each of the transponders of20×10GbE DS 512. Each of the transponders of 20×10GbE DS 512 may converta received corresponding 10GbE optical data signal, of the 10GbE opticaldata signals, into a corresponding electrical signal. More specifically,a first transceiver in each of the transponders may convert each of thetwenty 10GbE optical data signals into the corresponding electricalsignal. Each of the transponders may also comprise a second transceiverthat may convert the corresponding electrical signal into a SONET/SDHoptical data signal with a corresponding SONET/SDH optical data signalwavelength. In some embodiments, each of the twenty correspondingSONET/SDH optical data signals may have the same wavelength. In otherembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have unique wavelengths. The twenty transponders of 20×10GbEDS 512 may transmit the twenty SONET/SDH optical data signals to the MTCon the SONET/SDH optical network connection. In some embodiments, DWDM515 may output one or more 10GbE optical data signals (e.g., RPD DS 527)to a remote physical (PHY) device (RPD) (e.g., RPD 517). RPD 517 may besimilar to Remote PHY Node 207 in functionality. RPD 517 may convert theone or more 10GbE optical data signals into an electrical signal thatmay be transmitted over one or more coaxial cables. RPD 517 may alsoconvert one or more electrical signals into one or more 10GbE opticaldata signal for transmission to a transponder (e.g., 20×10GbE UP 514).

The operation of outside plant 550 may be further described by way ofthe processing of an upstream optical data signal transmitted to headend530. Each of the transponders of 20×10GbE UP 514 may receive a SONET/SDHoptical data signal from a MTC and each of the transponders may convertthe SONET/SDH optical data signal into an electrical signal. Morespecifically, a first transceiver in the transponder may convert theSONET/SDH optical data signal into an electrical signal. A secondtransceiver may then convert the electrical signal into a second opticaldata signal, wherein the second optical data signal comprises one ormore packets of light each of which may have a distinct wavelength.Because the one or more packets of light each have a distinctwavelength, the second optical data signal may be said to have thisdistinct wavelength. Thus, the twenty transponders in 20×10GbE UP 514may each receive a SONET/SDH optical data signal, and each of the twentytransponders may convert the received SONET/SDH optical data signal intoa corresponding second optical data signal, wherein each of thecorresponding second optical data signals has a unique wavelength. Thatis, the wavelength of each of the corresponding second optical datasignals is distinguishable from the wavelength of any of the othercorresponding second optical data signals. Thus 20×10GbE UP 514 maygenerate twenty corresponding second optical data signals each of whichhas a unique wavelength.

DWDM 519 may receive twenty corresponding second optical data signals asan input and output a multi-wavelength upstream optical data signal(e.g., multi-wavelength downstream optical data signal 569) to port 593of WDM 513. In some embodiments, RPD 517 may transmit one or more 10GbEoptical data signals (e.g., RPD UP 537) to one or more of 20×10GbE UP514. RPD UP 537 may be 10GbE optical data signals generated by RPD 517in response to RPD 517 receiving electrical signals on coaxial cablesconnecting a remote physical (PHY) network (e.g., remote PHY network216) to DWDM 519. The multi-wavelength upstream optical data signal 569may be a 10GbE optical data signal. More specifically, DWDM 519 maymultiplex the twenty corresponding second optical data signals onto thefiber, wherein the twenty multiplexed corresponding second optical datasignals compose the multi-wavelength upstream optical data signal. Themulti-wavelength optical data signal may have a wavelength comprisingthe twenty wavelengths of the twenty corresponding second optical datasignals.

WDM 513 may be a five port wave division multiplexer (WDM), or a fiveport circulator, that receives a multi-wavelength upstream optical datasignal on port 593. WDM 513 may also receive an XGPON/10GEPON signal,carried on a first fiber (e.g., XGPON/10GEPON 554), on port 595, a GPONsignal, carried on a second fiber (e.g., GPON 552), on port 596, and maymultiplex the multi-wavelength upstream optical data signal with theXGPON/10GEPON and GPON signal. XGPON/10GEPON 554 may be a fiber carryingan XGPON/10GEPON optical data signal with a wavelength within the 1571nm-1591 nm range. GPON 552 may be a fiber carrying a GPON optical datasignal with a wavelength of 1490 nm. WDM 513 outputs an egress opticaldata signal from port 584, which may be a multi-wavelength optical datasignal comprising 10GbE, XGPON/10GEPON, and/or GPON optical datasignals. WDM 513 may multiplex the multi-wavelength upstream opticaldata signal, the XGPON/10GEPON optical data signal, and GPON opticaldata signal the same way DWDM 507, 515, and 519 multiplex optical datasignals. The egress optical data signal (e.g., egress optical datasignal 583) may be output on port 584 of WDM 513 and optical switch 580may switch egress optical data signal 583 onto primary fiber 540 orsecondary fiber 511 depending on the position of switch 580. Egressoptical data signal 583 may be transmitted on primary fiber 540 to afirst connector at headend 530, or may be transmitted on secondary fiber511 to a second connector at headend 530.

The operation of headend 530 may be further described by way of theprocessing of an upstream optical data signal received from outsideplant 550. Egress optical data signal 583 may be received on the firstor second connector at headend 530 based on a position of optical switch508, as ingress optical data signal 543. That is ingress optical datasignal 543 may be similar to egress optical data signal 583. Ingressoptical data signal 543 may be received by WDM 509 via port 542.

WDM 509 may demultiplex ingress optical data signal 543 into amulti-wavelength upstream optical data signal 559, an XGPON/10GEPONoptical data signal that may be output on port 548 onto a first fiber(e.g., XGPON/10GEPON 534), and/or a GPON optical data signal output onport 549 onto a second fiber (e.g., GPON 532). The XGPON/10GEPON opticaldata signal may be received on XGPON/10GEPON port 503 and the GPONoptical data signal may be received on GPON port 501.

The multi-wavelength upstream optical data signal 559 may be output onport 545 and received by EDFA 541. The multi-wavelength upstream opticaldata signal 559 may comprise 10GbE optical data signals. A gainassociated EDFA 541 may be based at least in part on a distance that10GbE optical data signals have to travel, similar to that of EDFA 544.Multi-wavelength upstream optical data signal 559 may be amplified byEDFA 541, and EDFA 541 may output multi-wavelength upstream optical datasignal 529 to WDM 505. WDM 505 may receive the multi-wavelength upstreamoptical data signal 520 on port 543 of WDM 505. WDM 505 may outputmulti-wavelength upstream optical data signal 536 which is substantiallythe same as multi-wavelength upstream optical data signal 529. WDM 505may function as a circulator when receiving multi-wavelength upstreamoptical data signal 529 on port 543 and outputting multi-wavelengthupstream optical data signal 536 on port 542. Multi-wavelength upstreamoptical data signal 536 may be received by DWDM 507.

The multi-wavelength upstream optical data signal 536 may comprise 10GbEoptical data signals. DWDM 507 may demultiplex the multi-wavelengthupstream optical data signal 536 into individual optical data signals inaccordance with the individual wavelengths of the 10GbE optical datasignals. More specifically, the multi-wavelength upstream optical datasignal 536 may be demultiplexed into twenty 10GbE optical data signals,each of which may have a unique wavelength. DWDM 507 may output each ofthe twenty 10GbE optical data signals to each of the transponders of20×10GbE UP 506. Each of the transponders of 20×10GbE UP 506 may converta received corresponding 10GbE optical data signal, of the 10GbE opticaldata signals, into a corresponding electrical signal. More specifically,a first transceiver in each of the transponders may convert each of thetwenty 10GbE optical data signals into the corresponding electricalsignal. Each of the transponders may also comprise a second transceiverthat may convert the corresponding electrical signal into a SONET/SDHoptical data signal with a corresponding SONET/SDH optical data signalwavelength. In some embodiments, each of the twenty correspondingSONET/SDH optical data signals may have the same wavelength. In otherembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have unique wavelengths. The twenty transponders of 20×10GbEUP 506 may transmit the twenty SONET/SDH optical data signals to the MTCon the SONET/SDH optical network connection.

FIG. 6 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure. FIG. 6 shows a schematic of anOCML headend according to at least one embodiment of the disclosure. Asshown in FIG. 6, headend 630 is a smart integrated OCML headend, whichis a circuit, comprising a AWG (e.g., AWG 607), a first WDM (e.g., WDM605), a second WDM (e.g., WDM 609), a GPON port (e.g., GPON PORT 601),an XGPON/10GEPON port (e.g., XGPON/10GEPON PORT 603), a first EDFA(e.g., EDFA 641), a second EDFA (e.g., EDFA 643), and an optical switch613 to feed a primary optical fiber (e.g., Primary Fiber 617) orsecondary (backup) optical fiber (e.g., Secondary Fiber 627). AWG 607may be similar in functionality to DWDM 106 and WDM 605 and WDM 609 maybe similar in functionality to WDM 108. The disclosure provides a methodof transporting multiple 10GbE and GPON/XGPON/10GEPON signals on thesame optical fiber over extended links of up to 60 kms without a cablecompany having to put optical amplifiers between the cable's MasterTerminal Center (MTC) facility and a outside plant (e.g., Outside plant650) or field hub. The MTC facility may be an inside plant facilitywhere a cable company acquires and combines services to be offered tocustomers. The MTC facility provides these combined services tocustomers, by transmitting and receiving optical signals over aplurality of optical fibers to a field hub or outside plant whichconnects the plurality of optical fibers to a customer's premise. TheOCML headend may be located in a secondary terminal center (STC) thatconnects the MTC facility to a field hub or outside plant housing amultiplexer-demultiplexer (MDM) (e.g., MDM 208 in FIG. 2).

In one aspect, headend 630 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 604) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 606). 20×10GbE DS 604 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 606 mayreceive upstream data over 10GbE wavelengths. 20×10GbE DS 504 maycomprise the same elements and perform the same operations as 20×GbE DS190, and 20×10GbE UP 606 may comprise the same elements and perform thesame operations as 20×GbE UP 188.

The operation of headend 630 may be described by way of the processingof downstream optical data signals transmitted from headend 630 to aoutside plant (e.g., Outside plant 650) or field hub, and the processingof upstream optical data signals received from the field hub or outsideplant. Each of the transponders of 20×10GbE DS 604 may receive aSONET/SDH optical data signal from a MTC and each of the transpondersmay convert the SONET/SDH optical data signal into an electrical signal.More specifically, a first transceiver in the transponder may convertthe SONET/SDH optical data signal into an electrical signal. A secondtransceiver may then convert the electrical signal into a second opticaldata signal, wherein the second optical data signal comprises one ormore packets of light each of which may have a distinct wavelength.Because the one or more packets of light each have a distinctwavelength, the second optical data signal may be said to have thisdistinct wavelength. Thus, the twenty transponders in 20×10GbE DS 604may each receive a SONET/SDH optical data signal, and each of the twentytransponders may convert the received SONET/SDH optical data signal intoa corresponding second optical data signal, wherein each of thecorresponding second optical data signals has a unique wavelength. Thatis, the wavelength of each of the corresponding second optical datasignals is distinguishable from the wavelength of any of the othercorresponding second optical data signals. Thus 20×10GbE DS 604 maygenerate twenty corresponding second optical data signals each of whichhas a unique wavelength.

AWG 607 may receive the twenty corresponding second optical data signalsas an input and output a multi-wavelength downstream optical data signal(e.g., 638) comprising the twenty corresponding second optical datasignals onto a fiber. The multi-wavelength downstream optical datasignal 638 may be a 10GbE optical data signal. More specifically, AWG607 may multiplex the twenty corresponding second optical data signalsonto the fiber, wherein the twenty multiplexed corresponding secondoptical data signals compose the multi-wavelength downstream opticaldata signal. The multi-wavelength optical data signal may have awavelength comprising the twenty wavelengths of the twenty correspondingsecond optical data signals.

The multi-wavelength downstream optical data signal 638, may be input toWDM 605. WDM 605 may be a five port wave division multiplexer (WDM), ora five port circulator, that receives multi-wavelength downstreamoptical data signal 638 on port 602. WDM 605 may also receive anXGPON/10GEPON signal, carried on a first fiber (e.g., XGPON/10GEPON634), on port 610, a GPON signal, carried on a second fiber (e.g., GPON632), on port 667, and may multiplex multi-wavelength downstream opticaldata signal 638 with the XGPON/10GEPON and GPON signal. XGPON/10GEPON634 may be a fiber carrying an XGPON/10GEPON optical data signal with awavelength within the 1571 nm-1591 nm range. GPON 632 may be a fibercarrying a GPON optical data signal with a wavelength of 1490 nm or 1310nm. WDM 605 outputs an egress optical data signal from port 615, whichmay be a multi-wavelength optical data signal comprising 10GbE,XGPON/10GEPON, and/or GPON optical data signals. WDM 605 may multiplexmulti-wavelength downstream optical data signal 638, the XGPON/10GEPONoptical data signal, and GPON optical data signal the same way AWG 607multiplexes optical data signals.

WDM 605 may output multi-wavelength downstream optical data signal 639to an EDFA (e.g., EDFA 641). A gain of the EDFA may be based at least inpart on a distance that a downstream signal has to travel. For example,the gain may be a function of a fiber attenuation coefficient α, whichis a measure of the intensity of the attenuation of a beam of light asit traverses a length of an optical fiber segment. The unit ofmeasurement of the fiber attenuation coefficient is decibels (dB) per km(dB/km). For instance, the EDFA may be adjusted based at least in parton the attenuation coefficient and length of fiber that the egressoptical data signal will travel. More specifically, the gain EDFA 641may be G=e^((2αL)), where α is the fiber attenuation coefficient, asexplained above, and L is the length of the fiber (e.g., the length ofprimary fiber 617 and/or the length of secondary fiber 627).Multi-wavelength downstream optical data signal 639 may be amplified byEDFA 641, and EDFA 641 may output multi-wavelength downstream opticaldata signal 640 to port 615 of WDM 609. WDM 609 outputs an egressoptical data signal from port 616, which may be a multi-wavelengthoptical data signal comprising 10GbE, XGPON/10GEPON, and/or GPON opticaldata signals.

Egress optical data signal 620 by WDM 609 and optical switch 613 mayswitch egress optical data signal 620 onto primary fiber 617 orsecondary fiber 627 depending on the position of switch 613. Egressoptical data signal 620 may be transmitted on primary fiber 617 to port621 at passive optical component 625, or may be transmitted on secondaryfiber 627 to port 631 at passive optical component 625. Passive opticalcomponent 625 may output ingress optical data signal 656 from port 629to port 697 at WDM 673.

Ingress optical data signal 656 may be received by WDM 673 via port 697.WDM 673 may demultiplex ingress optical data signal 656 into amulti-wavelength downstream optical data signal 659, an XGPON/10GEPONoptical data signal that may be output on port 699 onto a first fiber(e.g., XGPON/10GEPON 654), and/or a GPON optical data signal output onport 698 onto a second fiber (e.g., GPON 652). The XGPON/10GEPON opticaldata signal may be received on XGPON/10GEPON port 653 and the GPONoptical data signal may be received on GPON port 651.

The multi-wavelength downstream optical data signal 659 may be output onport 696 and received by array waveguide gratings (AWG) AWG 675. Themulti-wavelength downstream optical data signal 659 may comprise 10GbEoptical data signals. AWG 675 may demultiplex the multi-wavelengthupstream optical data signal 659 into individual optical data signals inaccordance with the individual wavelengths of the 10GbE optical datasignals. More specifically, the multi-wavelength downstream optical datasignal 659 may be demultiplexed into twenty 10GbE optical data signals,each of which may have a unique wavelength. AWG 675 may output each ofthe twenty 10GbE optical data signals to each of the transponders of20×10GbE DS 612. Each of the transponders of 20×10GbE DS 612 may converta received corresponding 10GbE optical data signal, of the 10GbE opticaldata signals, into a corresponding electrical signal. More specifically,a first transceiver in each of the transponders may convert each of thetwenty 10GbE optical data signals into the corresponding electricalsignal. Each of the transponders may also comprise a second transceiverthat may convert the corresponding electrical signal into a SONET/SDHoptical data signal with a corresponding SONET/SDH optical data signalwavelength. In some embodiments, each of the twenty correspondingSONET/SDH optical data signals may have the same wavelength. In otherembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have unique wavelengths. The twenty transponders of 20×10GbEDS 612 may transmit the twenty SONET/SDH optical data signals to a RPD(e.g., RPD 677) on the SONET/SDH optical network connection. In someembodiments, AWG 675 may output one or more 10GbE optical data signals(e.g., RPD DS 627) RPD 677. RPD 677 may be similar to Remote PHY Node207 in functionality. RPD 677 may convert the one or more 10GbE opticaldata signals into an electrical signal that may be transmitted over oneor more coaxial cables. RPD 617 may also convert one or more electricalsignals into one or more 10GbE optical data signal for transmission to atransponder (e.g., 20×10GbE UP 614).

The operation of outside plant 650 may be further described by way ofthe processing of an upstream optical data signal transmitted to headend630. Each of the transponders of 20×10GbE UP 614 may receive a SONET/SDHoptical data signal from RPD 677 and each of the transponders mayconvert the SONET/SDH optical data signal into an electrical signal.More specifically, a first transceiver in the transponder may convertthe SONET/SDH optical data signal into an electrical signal. A secondtransceiver may then convert the electrical signal into a second opticaldata signal, wherein the second optical data signal comprises one ormore packets of light each of which may have a distinct wavelength.Because the one or more packets of light each have a distinctwavelength, the second optical data signal may be said to have thisdistinct wavelength. Thus, the twenty transponders in 20×10GbE UP 614may each receive a SONET/SDH optical data signal, and each of the twentytransponders may convert the received SONET/SDH optical data signal intoa corresponding second optical data signal, wherein each of thecorresponding second optical data signals has a unique wavelength. Thatis, the wavelength of each of the corresponding second optical datasignals is distinguishable from the wavelength of any of the othercorresponding second optical data signals. Thus 20×10GbE UP 614 maygenerate twenty corresponding second optical data signals each of whichhas a unique wavelength.

AWG 675 may receive twenty corresponding second optical data signals asan input and output a multi-wavelength upstream optical data signal(e.g., multi-wavelength upstream optical data signal 658) comprising thetwenty corresponding second optical data signals onto a fiber. In someembodiments, RPD 677 may transmit one or more 10GbE optical data signals(e.g., RPD UP 637) to one or more of 20×10GbE UP 614. RPD UP 637 may be10GbE optical data signals generated by RPD 677 in response to RPD 677receiving electrical signals on coaxial cables connecting a remotephysical (PHY) network (e.g., remote PHY network 216) to AWG 675. Themulti-wavelength upstream optical data signal 658 may be a 10GbE opticaldata signal. More specifically, AWG 675 may multiplex the twentycorresponding second optical data signals onto the fiber, wherein thetwenty multiplexed corresponding second optical data signals compose themulti-wavelength downstream optical data signal. The multi-wavelengthoptical data signal may have a wavelength comprising the twentywavelengths of the twenty corresponding second optical data signals.

The multi-wavelength upstream optical data signal 658, may be input toWDM 673. WDM 673 may be a four port wave division multiplexer (WDM), ora four port circulator, that receives multi-wavelength upstream opticaldata signal 658 on port 696. WDM 673 may also receive an XGPON/10GEPONsignal, carried on a first fiber (e.g., XGPON/10GEPON 654), on port 699,a GPON signal, carried on a second fiber (e.g., GPON 652), on port 698,and may multiplex multi-wavelength upstream optical data signal 658 withthe XGPON/10GEPON and GPON signal. XGPON/10GEPON 654 may be a fibercarrying an XGPON/10GEPON optical data signal with a wavelength withinthe 1571 nm-1591 nm range. GPON 652 may be a fiber carrying a GPONoptical data signal with a wavelength of 1490 nm or 1310 nm. WDM 673outputs an egress optical data signal from port 697, which may be amulti-wavelength optical data signal comprising 10GbE, XGPON/10GEPON,and/or GPON optical data signals. WDM 673 may multiplex multi-wavelengthupstream optical data signal 658, the XGPON/10GEPON optical data signal,and GPON optical data signal the same way AWG 675 multiplexes opticaldata signals. The egress optical data signal (e.g., egress optical datasignal 657) may be output on port 697 of WDM 673 to port 629 of passiveoptical component 625. Passive optical component 625 may switch egressoptical data signal 657 onto primary fiber 617 or secondary fiber 627depending on a position of a switch in passive optical component 625.Egress optical data signal 657 may be transmitted on primary fiber 617to a first port (e.g., port 615) at headend 630, or may be transmittedon secondary fiber 627 to a second port (e.g., port 623) at headend 630.

The operation of headend 630 may be further described by way of theprocessing of an upstream optical data signal received from outsideplant 650. Egress optical data signal 657 may be received on the firstor second connector at headend 630 based on a position of optical switch613, as ingress optical data signal 611. That is ingress optical datasignal 611 may be similar to egress optical data signal 657. Ingressoptical data signal 611 may be received by WDM 609 via port 616.

WDM 609 may demultiplex ingress optical data signal 611 into amulti-wavelength upstream optical data signal 619. The multi-wavelengthupstream optical data signal 619 may be output on port 618 and receivedby EDFA 643. The multi-wavelength upstream optical data signal 619 maycomprise 10GbE optical data signals. A gain associated EDFA 643 may bebased at least in part on a distance that 10GbE optical data signalshave to travel, similar to that of EDFA 641. Multi-wavelength upstreamoptical data signal 619 may be amplified by EDFA 643, and EDFA 643 mayoutput multi-wavelength upstream optical data signal 633 to WDM 605. WDM605 may receive the multi-wavelength upstream optical data signal 633 onport 608 of WDM 605. WDM 605 may output multi-wavelength upstreamoptical data signal 636 which is substantially the same asmulti-wavelength upstream optical data signal 633. WDM 605 may functionas a circulator when receiving multi-wavelength upstream optical datasignal 633 on port 608 and outputting multi-wavelength upstream opticaldata signal 636 on port 602. Multi-wavelength upstream optical datasignal 636 may be received by AWG 607.

The multi-wavelength upstream optical data signal 636 may comprise 10GbEoptical data signals. AWG 607 may demultiplex the multi-wavelengthupstream optical data signal 636 into individual optical data signals inaccordance with the individual wavelengths of the 10GbE optical datasignals. More specifically, the multi-wavelength upstream optical datasignal 636 may be demultiplexed into twenty 10GbE optical data signals,each of which may have a unique wavelength. AWG 607 may output each ofthe twenty 10GbE optical data signals to each of the transponders of20×10GbE UP 606. Each of the transponders of 20×10GbE UP 606 may converta received corresponding 10GbE optical data signal, of the 10GbE opticaldata signals, into a corresponding electrical signal. More specifically,a first transceiver in each of the transponders may convert each of thetwenty 10GbE optical data signals into the corresponding electricalsignal. Each of the transponders may also comprise a second transceiverthat may convert the corresponding electrical signal into a SONET/SDHoptical data signal with a corresponding SONET/SDH optical data signalwavelength. In some embodiments, each of the twenty correspondingSONET/SDH optical data signals may have the same wavelength. In otherembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have unique wavelengths. The twenty transponders of 20×10GbEUP 606 may transmit the twenty SONET/SDH optical data signals to the MTCon the SONET/SDH optical network connection.

FIG. 7 depicts different passive optical network (PON) transceiverparameters associated with downstream transmitting circuits and upstreamtransmitting circuits, in accordance with the disclosure. Parameters700, comprise a wavelength column (i.e., wavelength 701), a transmission(Tx) power column (i.e., Tx power 702), a dispersion penalty column(i.e., dispersion power 703), a loss budget column (i.e., loss budget705), and a minimum receive power column (i.e., minimum receive power709) for different passive optical network (PON) transceivers (i.e.,GPON C+ 711, XGPON/10GEPON N2a 721, or XGPON/10GEPON N1 731).

Wavelength 701 may include the wavelength of a downstream optical datasignal (i.e., downstream 712, downstream 722, and downstream 732)transmitted by each of PON transceivers GPON C+ 711, XGPON/10GEPON N2a721, or XGPON/10GEPON N1 731 at an OCML headend to a corresponding PONtransceiver at a outside plant. Wavelength 701 may include thewavelength of an upstream optical data signal (i.e., upstream 713,upstream 723, and upstream 733) received by each of PON transceiversGPON C+ 711, XGPON/10GEPON N2a 721, or XGPON/10GEPON N1 731 at an OCMLheadend from a corresponding PON transceiver at a outside plant. Thedownstream optical data signal may be an optical data signal sent froman OCML headend to a outside plant, as disclosed herein. The upstreamoptical data signal may be an optical data signal received at the OCMLheadend from a outside plant, as disclosed herein.

Tx power 702 may include the transmission power of the downstreamoptical data signal (i.e., downstream 712, downstream 722, anddownstream 732) from each of PON transceivers GPON C+ 711, XGPON/10GEPONN2a 721, or XGPON/10GEPON N1 731 at an OCML headend to a correspondingPON transceiver at a outside plant. Tx power 702 may include thetransmission power of the upstream optical data signal (i.e., upstream713, downstream 723, and downstream 733) transmitted by each of PONtransceivers GPON C+ 711, XGPON/10GEPON N2a 721, or XGPON/10GEPON N1 731at a outside plant to a corresponding PON transceiver at an OCMLheadend.

Dispersion penalty 703 may include a power dispersion penalty associatedwith the downstream optical data signal (i.e., downstream 712,downstream 722, and downstream 732) being transmitted by each of PONtransceivers GPON C+ 711, XGPON/10GEPON N2a 721, or XGPON/10GEPON N1 731on a fiber from an OCML headend to a corresponding PON transceiver at aoutside plant. Dispersion penalty 703 may include a power dispersionpenalty associated with the upstream optical data signal (i.e.,downstream 713, downstream 723, and downstream 733) being received byeach of PON transceivers GPON C+ 711, XGPON/10GEPON N2a 721, orXGPON/10GEPON N1 731 at an OCML headend from a corresponding PONtransceiver at a outside plant.

In some embodiments, an optical data signal may experience dispersion asit travels through an optical fiber. The dispersion penalty may be basedat least in part on a bandwidth of the optical fiber, a dispersionconstant for a given wavelength carrying the optical data signal, thelength of the optical fiber, and a wavelength spread of a lasergenerating the optical data signal. More specifically the dispersionpenalty may be determined by the expression PP_(D)(B, D, L,σ_(λ))=5*log[1+2*π*(B*D*L*σ_(λ))²]. B is the bandwidth of the opticalfiber carrying the optical data signal, D is the dispersion constant,Lis the length of the optical fiber, and σ_(λ) is the wavelength spreadof the laser. B and L may be constants that are determined during adesign of fiber to the home (FTTH) network like the one depicted in FIG.2. D may be based at least in part a zero dispersion wavelength for theoptical data signal, a dispersion wavelength of the optical data signal,and a slope of the dispersion characteristic for the zero dispersionwavelength of the optical data signal. Specifically, D may be equal to

${\frac{S_{0}}{4}*\left( {\lambda - \frac{\lambda_{0}^{4}}{\lambda^{3}}} \right)},$wherein S₀ is the slope of the dispersion characteristic for the zerodispersion wavelength (λ₀) of the optical data signal. The zerodispersion wavelength may be the wavelength at which material dispersionand waveguide dispersion cancel one another out. λ may be the dispersionwavelength of the optical data signal. The units of S₀ may bepicoseconds per the product of nanometers squared and kilometer (i.e.,

$\left( {{i.e.},{\left. \frac{ps}{{nm}^{2}*{km}} \right).}} \right.$

Loss budget 705 may include a loss budget associated with the downstreamoptical data signal (i.e., downstream 712, downstream 722, anddownstream 732) being transmitted by each of PON transceivers GPON C+711, XGPON/10GEPON N2a 721, or XGPON/10GEPON N1 731 at an OCML headendto a corresponding PON transceiver at a outside plant along a fiberconnecting the OCML headend and outside plant. Loss budget 705 mayinclude a loss budget associated with the upstream optical data signal(i.e., downstream 713, downstream 723, and downstream 733) beingreceived by each of PON transceivers GPON C+ 711, XGPON/10GEPON N2a 721,or XGPON/10GEPON N1 731 at an OCML headend from a corresponding PONtransceiver at a outside plant along a fiber connecting the OCML headendand outside plant.

Minimum receive power 709 may include a minimum receive power necessaryfor each of PON transceivers GPON C+ 711, XGPON/10GEPON N2a 721, orXGPON/10GEPON N1 731, at a outside plant, to correctly decode one ormore bits received from a corresponding PON transceiver at an OCMLheadend in a downstream optical data signal (i.e., downstream 712,downstream 722, and downstream 732). For instance, a minimum receivepower level may be necessary for each of PON transceivers GPON C+ 711,XGPON/10GEPON N2a, or XGPON/10GEPON N1 731 to correctly detect a bitvalue of “1”, at the outside plant, when a bit value of “1” istransmitted by a corresponding PON transceiver at an OCML headend.Minimum receive power 709 may include a minimum receive power necessaryfor each of PON transceivers GPON C+ 711, XGPON/10GEPON N2a, at an OCMLheadend, to correctly decode one or more bits received from acorresponding transceiver at a outside plant in an upstream optical datasignal. For instance, a minimum receive power level may be necessary foreach of PON transceivers GPON C+ 711, XGPON/10GEPON N2a, orXGPON/10GEPON N1 731 to correctly detect a bit value of “1”, at the OCMLheadend, when a bit value of “1” is transmitted by a corresponding PONtransceiver at the outside plant.

In some embodiments, a GPON C+ transceiver (i.e., GPON C+ 711), at anOCML headend, may transmit a downstream (i.e., downstream 712) opticaldata signal with a wavelength (i.e., wavelength 701) of 1490 nanometers,a Tx power (i.e., Tx power 702) between 3 and 7 decibel-milliwatts, adispersion penalty (i.e., dispersion penalty 703) of 1 decibel, a lossbudget (i.e., loss budget 705) of 32 decibels, and a minimum receivepower (i.e., minimum receive power 709) of −30 decibels to a GPON C+transceiver at a outside plant.

In some embodiments, a GPON C+ transceiver (i.e., GPON C+ 711), at aoutside plant, may transmit an upstream (i.e., upstream 713) opticaldata signal, with a wavelength (i.e., wavelength 701) of 1310nanometers, a Tx power (i.e., Tx power 702) between 0.5 and 5decible-milliwatts, a dispersion penalty (i.e., dispersion penalty 703)of 0.5 decibel, a loss budget (i.e., loss budget 705) of 32 decibels,and a minimum receive power (i.e., minimum receive power 709) of −32decibels to a GPON C+ transceiver at an OCML headend.

In some embodiments, an XGPON/10GEPON N2a transceiver (i.e.,XGPON/10GEPON N2a 721), at an OCML headend, may transmit a downstream(i.e., downstream 722) optical data signal with a wavelength (i.e.,wavelength 701) of 1575 nanometers, a Tx power (i.e., Tx power 702)between 4 and 8 decibel-milliwatts, a dispersion penalty (i.e.,dispersion penalty 703) of 1 decibel, a loss budget (i.e., loss budget705) of 31 decibels, and a minimum receive power (i.e., minimum receivepower 709) of −28 decibels to an XGPON/10GEPON N2a transceiver at aoutside plant.

In the same, or a similar embodiment, an XGPON/10GEPON N2a transceiver(i.e., XGPON/10GEPON N2a 721), at a outside plant, may transmit anupstream (i.e., upstream 723) optical data signal, with a wavelength(i.e., wavelength 701) of 1270 nanometers, a Tx power (i.e., Tx power702) between 2 and 7 decible-milliwatts, a dispersion penalty (i.e.,dispersion penalty 703) of 0.5 decibel, a loss budget (i.e., loss budget705) of 31 decibels, and a minimum receive power (i.e., minimum receivepower 709) of −29.5 decibels to an XGPON/10GEPON N2a transceiver at anOCML headend.

In some embodiments, an XGPON/10GEPON N1 transceiver (i.e.,XGPON/10GEPON N1 731), at an OCML headend, may transmit a downstream(i.e., downstream 732) optical data signal with a wavelength (i.e.,wavelength 701) of 1575 nanometers, a Tx power (i.e., Tx power 702)between 2 and 6 decibel-milliwatts, a dispersion penalty (i.e.,dispersion penalty 703) of 1 decibel, a loss budget (i.e., loss budget705) of 31 decibels, and a minimum receive power (i.e., minimum receivepower 709) of −28 decibels to an XGPON/10GEPON N1 transceiver at aoutside plant.

In the same, or a similar embodiment, an XGPON/10GEPON N1 transceiver(i.e., XGPON/10GEPON N1 731), at a outside plant, may transmit anupstream (i.e., upstream 733) optical data signal, with a wavelength(i.e., wavelength 701) of 1270 nanometers, a Tx power (i.e., Tx power702) between 2 and 7 decible-milliwatts, a dispersion penalty (i.e.,dispersion penalty 703) of 0.5 decibel, a loss budget (i.e., loss budget705) of 29 decibels, and a minimum receive power (i.e., minimum receivepower 709) of −27.5 decibels to an XGPON/10GEPON N1 transceiver at anOCML headend.

FIG. 8 depicts a graphical representation of wavelengths used totransport one or more signals, in accordance with the disclosure. OCMLoptical wavelengths 801 illustrate the different wavelengths of theoptical data signals described herein. For GPON optical data signalsdisclosed herein, a wavelength of 1310 nm may be used to transmit anupstream GPON optical data signal from a outside plant to an OCMLheadend. For GPON optical data signals disclosed herein, a wavelength of1490 nm may be used to transmit a downstream GPON optical data signalfrom the OCML headend o the outside plant. For 10GbE optical datasignals disclosed herein, a wavelength between 1530 and 1565 nm may beused to transmit an upstream 10GbE optical data signal to the OCMLheadend from the outside plant, and to transmit a downstream 10GbEoptical data signal to the outside plant from the OCML headend. In someembodiments, the upstream XGPON/10GEPON optical data signals disclosedherein may have wavelengths between 1260 nm and 1280 nm (e.g.,XGPON/10GEPON 802). In some embodiments, the downstream XGPON/10GEPONoptical data signals disclosed herein may have wavelengths between 1571nm and 1591 nm.

FIG. 9 depicts a stimulated Raman scattering (SRS) diagram, inaccordance with the disclosure. Raman gain spectrum 900 may be Ramangain coefficients for an optical fiber comprised of silica andGermania-oxide (GeO₂). Raman gain spectrum 900 may be a plot of Ramangain coefficients against different wavelengths (i.e., wavelength 903).SRS is a nonlinear process where higher frequency optical channels aredepleted and lower frequency optical channels are amplified. With eachoptical channel being modulated, the intensity of higher frequencyoptical data signals modulate the intensity of lower frequency opticaldata signals. As a result, SRS may lead to optical crosstalk betweenchannels. The optical crosstalk due to SRS may be referred to as SRSoptical crosstalk, and may be defined by the following expression

${XT}_{{SRS},i} = {P^{2}{\sum\limits_{k \neq i}{{g^{2}/{{Aeff}_{i,k}^{2}\left( {\left( {1 - e^{- {aL}}} \right)^{2} + {4e^{- {aL}}{\sin^{2}\left( \frac{\Omega\; d_{i,k}L}{2} \right)}}} \right)}}/{\left( {a^{2} + {\Omega^{2}d_{i,k}^{2}}} \right).}}}}$That is the optical crosstalk experienced on a channel “i” (XT_(SRS,i))is based at least in part on the square of the optical fiber launchpower per channel (P) at which an optical data signal is transmitted.The optical crosstalk may also based at least in part on Raman gaincoefficients (g_(i,k) ²) between channel “i” and a channel “k”. TheRaman gain coefficients may be based at least in part on a Raman gainslope and the frequency at which optical data signals on channel “i” arepropagating and the frequency at which optical data signals on channel“k” are propagating. The optical crosstalk may also be based at least inpart on a fiber loss (α) and length (L) of the optical fiber. Theoptical crosstalk may also be based at least in part on a subcarriermodulation frequency (Ω) and a group velocity mismatch between opticaldata signals propagating on channel “i” and optical data signalspropagating on channel “k” (d_(i,k)).

Depending on the wavelength separation between the optical data signalspropagating on channel “i” and the optical data signals propagating onchannel “k”, polarization states of the optical data signals in channels“i′” and “k”, the optical fiber launch powers for channels “i”′ and “k”SRS optical crosstalk may occur which depletes shorter (pump depletion902) wavelengths (e.g., GPON 1490 nm) and amplifies the higher (stokes)wavelengths resulting in signal degradation for certain optical datasignals (e.g., 10GbE optical data signal degradation 901). In someembodiments, the effect is on lower RF frequencies carried on longerwavelength optical data signals. Because of this interference from aGPON optical data signal with a wavelength of 1490 nm may causeinterference or signal degradation of a 10GbE optical data signal with awavelength of 1560 nm. In some embodiments, the SRS optical crosstalkmay be 35 dB which may result in a tolerable BER.

FIG. 10 depicts a schematic illustration of wavelength and optical fibermonitoring of cascaded OCML headends in accordance with the disclosure.Headend 1001 is a smart integrated OCML headend, which is a circuit,comprising one or more EDFAs (e.g., Booster Optical amplifiers 1012 and1019), a DWDM (e.g., DWDM 1007), one or more WDMs (e.g., WDM 1008 and1023), one or more DCMs (e.g., DCM 1018 and 1015), and an optical switch1027 to feed a primary optical fiber (e.g., Primary Fiber 1031) orsecondary (backup) optical fiber (e.g., Secondary Fiber 1032). The OCMLheadend may be located in a secondary terminal center (STC) thatconnects the MTC facility to a outside plant or field hub housing amultiplexer-demultiplexer (MDM) (e.g., MDM 208 in FIG. 2).

In one aspect, headend 1001 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 1003) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 1004). 20×10GbE DS 1003 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 1004 mayreceive upstream data over 10GbE wavelengths. Headend 1001 may comprisetwo PON 1002 connectors, one of which may be a GPON connector (e.g.,GPON 1006) and one of which may be an XGPON/10GEPON connector (e.g.,XGPON/10GEPON 1005). Headend 1001 may also comprise twowavelength-monitoring ports (e.g., wavelength-monitoring ports 1039), aprimary optical fiber (e.g., primary optical fiber 1031) and a secondaryoptical fiber (e.g., secondary optical fiber 1032) that transmit andreceive a plurality of multi-wavelength 10GbE and GPON/XGPON/10GEPONoptical signals. Primary optical fiber 1031 and secondary optical fiber1032 may transmit a first plurality of multi-wavelength 10GbE, GPON,and/or XGPON/10GEPON optical signals from headend 1001 to a outsideplant (not illustrated in FIG. 10), and may receive a second pluralityof multi-wavelength 10GbE, GPON, and/or XGPON/10GEPON optical signalsfrom the outside plant.

The operation of headend 1001 may be described by way of the processingof downstream optical data signals transmitted from headend 1001 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. Each of thetransponders of 20×10GbE DS 1003 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 1003 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 1003 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 1007 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 1098) comprising the twenty correspondingsecond optical data signals onto a fiber. More specifically, DWDM 1007may multiplex the twenty corresponding second optical data signals ontothe fiber, wherein the twenty multiplexed corresponding second opticaldata signals compose the multi-wavelength downstream optical datasignal. The multi-wavelength downstream optical data signal may have awavelength comprising the twenty wavelengths of the twenty correspondingsecond optical data signals.

The multi-wavelength downstream optical data signal 10GbE DS 1098, maybe input to a WDM (e.g. WDM 1008). WDM 1008 may be a three port wavedivision multiplexer (WDM), or a three port circulator, that receives10GbE DS 1098 on port 1010 and outputs 10GbE DS 1098 on port 1009 as10GbE DS 1013. 10GbE DS 1013 may be substantially the same as 10GbE DS1098 because WDM 1008 may function as a circulator when 10GbE DS 1098 isinput on port 1010.

WDM 10GbE DS 1013 may be input to an EDFA (e.g., booster opticalamplifier 1012). A gain of the booster optical amplifier (e.g., boosteroptical amplifier 1012) may be based at least in part on a distance thata downstream signal has to travel. For example, the gain may be afunction of a fiber attenuation coefficient α, which is a measure of theintensity of the attenuation of a beam of light as it traverses a lengthof an optical fiber segment. The unit of measurement of the fiberattenuation coefficient is decibels (dB) per km (dB/km). For instance,the gain of booster optical amplifier 1012 may be adjusted based atleast in part on the attenuation coefficient and length of fiber thatthe egress optical data signal will travel. More specifically, the gainof booster optical amplifier 1012 may be G=e^((2αL)), where α is thefiber attenuation coefficient, as explained above, and L is the lengthof the fiber (e.g., the length of primary fiber 1031 and/or the lengthof secondary fiber 1032). 10GbE DS 1013 may be amplified by boosteroptical amplifier 1012, and booster optical amplifier 1012 may output10GbE DS 1017 to DCM 1018.

10GbE DS 1017 may be input into a DCM (e.g., DCM 1012) to compensate fordispersion that 10GbE DS 1017 may experience after being amplified by anEDFA and multiplexed by a WDM, with other optical data signals, that aredownstream from the DCM. The amplified and multiplexed optical datasignal may be referred to as an egress optical data signal, as it is theoptical data signal that may be transmitted out of headend 1001 over afiber connecting headend 1001 to a field hub or outside plant. In someembodiments, DCM 1018 may be configured to balance positive and/ornegative dispersion that may be introduced to the egress optical datasignal by the fiber. In some embodiments, DCM 1018 may be configured tocompensate for positive (temporal broadening of the egress optical datasignal) and/or negative (temporal contraction of the egress optical datasignal) dispersion introduced by fiber that is 80 km or greater inlength, to reduce the sensitivity or OSNR levels of a transceiver in aDWDM located at a field hub or outside plant. More specifically, DCM1018 may be configured to reduce the sensitivity or OSNR levelrequirement in a photodetector or fiber-optic sensor in the transceiver,which may drastically reduce the cost of the transceivers used in theDWDM located at the field hub or outside plant.

WDM 1023 may be a WDM that may multiplex 10GbE DS 1022 with one or morePON signals carried on XGPON/10GEPON 1005 and GPON 1006. 10GbE DS 1022may be a multi-wavelength optical data signal, wherein the wavelengthscomprise the same wavelengths as 10GbE DS 1022. In some embodiments, thewavelengths of the multi-wavelength optical data signal 10GbE DS 1022may be within the conventional c band of wavelengths, which may includewavelengths within the 1520 nm-1565 nm range. XGPON/10GEPON 1005 may bea fiber carrying an XGPON/10GEPON optical data signal with a wavelengthwithin the 1571 nm-1591 nm or 1260 nm-1280 nm range. GPON 1006 may be afiber carrying a GPON optical data signal with a wavelength of 1490 nmor 1310 nm. The XGPON/10GEPON optical signal may be input to WDM 1023 onport 1021 and the GPON optical signal may be input to WDM 110 on port160. WDM 1023 outputs an egress optical data signal from port 1025,which may be a multi-wavelength optical data signal comprising 10GbE,XGPON/10GEPON, and GPON optical data signals. WDM 1023 may multiplex10GbE DS 1022, the XGPON/10GEPON optical data signal, and GPON opticaldata signal the same way DWDM 1007 multiplexes optical data signals. Theegress optical data signal (e.g., egress optical data signal 1020) maybe output on port 1025 of WDM 1023 and optical switch 1027 may switchegress optical data signal 1020 out of connector 1029 or connector 1034.In some embodiments, connector 1029 may be a primary connector andconnector 1034 may be a secondary connector or a backup connector.Wavelength monitoring connector 1039 may connect connector 1028 to afirst port of wavelength-monitoring ports 1039, and wavelengthmonitoring connector 1034 may connect connector 1035 to a second port ofwavelength-monitoring ports 1039. Wavelength-monitoring ports 1039 maymonitor the wavelengths in egress optical data signal 1020 via connector1029 or connector 1034 depending on the position of switch 1027. Egressoptical data signal 1020 may exit headend 1001 either via connector 1030connected to primary fiber 1031 or via connector 1033 connected tosecondary fiber 1032 depending on the position of switch 1027. Egressoptical data signal 1020 may be transmitted on primary fiber 1031 to afirst connector in the field hub or outside plant, or may be transmittedon secondary fiber 1032 to a second connector in the field hub oroutside plant. The field hub or outside plant may include a MDM with thefirst connector and the second connector.

The operation of headend 1001 may be described by way of the processingof upstream optical data signals received at headend 1001 from a fieldhub or outside plant. For instance, a multi-wavelength ingress opticaldata signal, comprising one or more of a 10GbE optical data signal,XGPON/10GEPON optical data signal, and/or GPON optical data signal, maybe an upstream optical data signal received on primary fiber 1031 orsecondary fiber 1032 depending on the position of switch 1027. Becausethe multi-wavelength ingress optical data signal is routed to port 1025of WDM 1023, and is altered negligibly between connector 1028 and port1025 or connector 1035 and port 1025, depending on the position ofswitch 1027, the multi-wavelength ingress optical data signal may besubstantially the same as ingress optical data signal 1026. Themulti-wavelength ingress optical data signal may traverse connector 1028and switch 1027, before entering WDM 1023 via port 1025 if switch 1027is connected to connector 1028. The multi-wavelength ingress opticaldata signal may traverse connector 1035 and switch 1027, before enteringWDM 1023 via port 1025 if switch 1027 is connected to connector 1350.WDM 1023 may demultiplex one or more 10GbE optical data signals,XGPON/10GEPON optical data signals, and/or GPON optical data signalsfrom ingress optical data signal 1026. WDM 1023 may transmit the one ormore XGPON/10GEPON optical data signals along XGPON/10GEPON 1005 to oneof PON connectors 1002 via port 1024. WDM 1023 may transmit the one ormore GPON optical data signals along GPON 1006 to one of PON connectors1002 via port 1021. WDM 1023 may transmit the one or more 10GbE opticaldata signals (e.g., 10GbE UP 1038) out of port 1037 to BOA 1019.

A gain of BOA 1019 may be based at least in part on a distance that theSONET/SDH egress optical data signal has to travel. For example, thegain may be a function of a fiber attenuation coefficient α, which is ameasure of the intensity of the attenuation of a beam of light as ittraverses a length of an optical fiber segment on the SONET/SDH opticalnetwork connection. For instance, the gain of BOA 1019 may be adjustedbased at least in part on the attenuation coefficient and length offiber that the egress optical data signal will travel. Morespecifically, the gain of BOA 1019 may be G=e^((2αL)), where α is thefiber attenuation coefficient, as explained above, and L is the lengthof the fiber (e.g., the length of the fiber of the SONET/SDH opticalnetwork connection). 10GbE UP 1038 may be amplified by BOA 1019, and BOA1019 may output 10GbE UP 1014 to DCM 1015.

The wavelength of 10GbE UP 1014 may be within the conventional c band ofwavelengths, which may include wavelengths within the 1520 nm-1565 nmrange. The one or more XGPON/10GEPON optical data signals may have awavelength within the 1571 nm-1591 nm or 1260 nm-1280 nmrange, and theone or more GPON optical data signals may have a wavelength of 1490 nm.

In some embodiments, DCM 1015 may be configured to balance positiveand/or negative dispersion that may be introduced to a SONET/SDH egressoptical data signal that may enter headend 1001 from 20×10GbE UP 1004.The SONET/SDH egress optical data signal may be an upstream signal froma field hub or outside plant destined for a MTC. For example, a customerpremise may be connected to the field hub or outside plant and may sendone or more packets via a SONET/SDH network to the field hub or outsideplant which may in turn transmit the one or more packets using 10GbEoptical data signals to headend 1001. The one or more packets may bedestined for a company web server connected to the MTC via a backbonenetwork. Because headend 1001 may be collocated in a STC that isconnected to the MTC via an optical ring network, wherein the connectionbetween the STC and MTC is an SONET/SDH optical network connection, DCM1015 may be configured to compensate for positive and/or negativedispersion on the SONET/SDH optical network connection. That is DCM 1015may be configured to reduce temporal broadening of the SONET/SDH egressoptical data signal or temporal contraction of the SONET/SDH egressoptical data signal. DCM 1015 may input 10GbE UP 1016 and my output10GbE UP 1014 to WDM 1008.

WDM 1008 may receive 10GbE UP 1014 on port 1011, and may output 10GbE UP1009 on port 1010 as a multi-wavelength upstream optical data signal(e.g., 10GbE UP 1009). 10GbE UP 1098 is substantially the same as 10GbEUP 1014 because WDM 1008 may function as a circulator when 10GbE UP 1014is input to port 1011. 10GbE UP 1009 may be received by DWDM 1007, andDWDM may demultiplex one or more 10GbE optical data signals from 10GbEUP 1009. Because 10GbE UP 1009 is a dispersion compensated amplifiedversion of the multi-wavelength ingress optical data signal, DWDM 1007may demultiplex the one or more optical data signals into individualoptical data signals in accordance with the individual wavelengths ofany 10GbE optical data signals in the multi-wavelength ingress opticaldata signal. More specifically, 10GbE UP 1009 may be demultiplexed intotwenty 10GbE optical data signals, each of which may have a uniquewavelength. DWDM 1007 may output each of the twenty 10GbE optical datasignals to each of the transponders of 20×10GbE UP 1004. Each of thetransponders of 20×10GbE UP 1004 may convert a received corresponding10GbE optical data signal, of the 10GbE optical data signals, into acorresponding electrical signal. More specifically, a first transceiverin each of the transponders may convert each of the twenty 10GbE opticaldata signals into the corresponding electrical signal. Each of thetransponders may also comprise a second transceiver that may convert thecorresponding electrical signal into a SONET/SDH optical data signalwith a corresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 1014 may transmitthe twenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

Headend 1086 and the components therein may be similar in function tothe components in headend 1001. Optical line monitor 1011 ports c and gmay be connected to wavelength-monitoring ports 1039 and optical linemonitor 1011 ports b and f may be connected to wavelength-monitoringports 1084. Optical line monitor 1011 may . . .

FIG. 11 a schematic illustration of wavelength and optical fibermonitoring of an OCML headend in accordance with the disclosure. Headend1102 and the components therein may be similar in function to thecomponents in headend 1001. Optical line monitor 1011 ports a and e maybe connected to wavelength-monitoring ports 1178. Optical line monitor1011 may . . .

FIG. 12 depicts an access network diagram of an OCML headend comprisingwavelength division multiplexers (WDMs), a dense wavelength divisionmultiplexer (DWDM), and optical amplifiers, in accordance with thedisclosure. FIG. 12 shows a schematic of an OCML headend according to atleast one embodiment of the disclosure. As shown in FIG. 12, headend1201 is a smart integrated OCML headend, which is a circuit, comprisinga DWDM (e.g., DWDM 1205), a first WDM (e.g., WDM 1210), a second WDM(e.g., WDM 1220), a GPON/EPON connector (e.g., GPON/EPON 1218), abooster amplifier BOA (e.g., BOA 1215), an optical pre-amplifier (OPA)(e.g., OPA 1214), an optical switch 1226 to feed a primary optical fiber(e.g., Primary Fiber 1235) via a primary variable optical attenuator(VOA) (e.g., VOA 1231) or secondary (backup) optical fiber (e.g.,Secondary Fiber 1236) via a secondary variable optical attenuator (VOA)(e.g., VOA 1232). DWDM 1205 may be similar in functionality to DWDM 106and WDM 1210 and WDM 1220 may be similar in functionality to WDM 108.The disclosure provides a method of transporting multiple 10GbE andGPON/EPON signals on the same optical fiber over extended links of up to60 kms without a cable company having to put optical amplifiers betweenthe cable's Master Terminal Center (MTC) facility and a field hub oroutside plant. The MTC facility may be an inside plant facility where acable company acquires and combines services to be offered to customers.The MTC facility provides these combined services to customers, bytransmitting and receiving optical signals over a plurality of opticalfibers to a field hub or outside plant which connects the plurality ofoptical fibers to a customer's premise. The OCML headend may be locatedin a secondary terminal center (STC) that connects the MTC facility to afield hub or outside plant housing a multiplexer-demultiplexer (MDM)(e.g., MDM 208 in FIG. 2).

The EPON signals may operate with the same optical frequencies as GPONand time division multiple access (TDMA). The raw line data rate is 1.25Gbits/s in both the downstream and upstream directions.

EPON is fully compatible with other Ethernet standards, so no conversionor encapsulation is necessary when connecting to Ethernet-based networkson either end. The same Ethernet frame is used with a payload of up to1518 bytes. EPON may not use a carrier sense multiple access(CSMA)/collision detection (CD) access method used in other versions ofEthernet.

There is a 10-Gbit/s Ethernet version designated as 802.3ay. The linerate may be 10.3125 Gbits/s. The primary mode is 10 Gbits/s upstream aswell as downstream. A variation uses 10 Gbits/s downstream and 1 Gbit/supstream. The 10-Gbit/s versions use different optical wavelengths onthe fiber, 1571 to 1591 nm downstream and 1260 to 1280 nm upstream sothe 10-Gbit/s system can be wavelength multiplexed on the same fiber asa standard 1-Gbit/s system.

In one aspect, headend 1201 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 1203) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 1204). 20×10GbE DS 1203 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 1204 mayreceive upstream data over 10GbE wavelengths. 20×10GbE DS 1203 maycomprise the same elements and perform the same operations as 20×GbE DS190, and 20×10GbE UP 1204 may comprise the same elements and perform thesame operations as 20×GbE UP 188.

The operation of headend 1201 may be described by way of the processingof downstream optical data signals transmitted from headend 1201 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. Each of thetransponders of 20×10GbE DS 1203 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 1203 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 1203 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 1205 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 1206) comprising the twenty correspondingsecond optical data signals onto a fiber. The multi-wavelengthdownstream optical data signal 10GbE DS 1206 may be a 10GbE optical datasignal. More specifically, DWDM 1205 may multiplex the twentycorresponding second optical data signals onto the fiber, wherein thetwenty multiplexed corresponding second optical data signals compose themulti-wavelength downstream optical data signal. The multi-wavelengthoptical data signal may have a wavelength comprising the twentywavelengths of the twenty corresponding second optical data signals.

The multi-wavelength downstream optical data signal 10GbE DS 1206, maybe input to WDM 1210. WDM 1210 may be a three port circulator, thatreceives multi-wavelength downstream optical data signal 10GbE DS 1206on port 1208, and outputs multi-wavelength downstream optical datasignal 10GbE DS 1206, on port 1211 as multi-wavelength downstreamoptical data signal 10GbE DS 1213 to BOA 1215.

BOA 1215 may have a gain that is based at least in part on a distancethat a downstream signal has to travel. For example, the gain may be afunction of a fiber attenuation coefficient α, which is a measure of theintensity of the attenuation of a beam of light as it traverses a lengthof an optical fiber segment. The unit of measurement of the fiberattenuation coefficient is decibels (dB) per km (dB/km). For instance,BOA 1215 may be adjusted based at least in part on the attenuationcoefficient and length of fiber that the egress optical data signal willtravel. More specifically, the gain BOA 1215 may be G=e^((2αL)), where αis the fiber attenuation coefficient, as explained above, and L is thelength of the fiber (e.g., the length of primary fiber 1235 and/or thelength of secondary fiber 1236). Multi-wavelength downstream opticaldata signal 10GbE DS 1213 may be amplified by BOA 1215, and BOA 1215 mayoutput multi-wavelength downstream optical data signal 10GbE DS 1216 toport 1217 of WDM 1220. WDM 1220 outputs an egress optical data signalfrom port 1219, which may be a multi-wavelength optical data signalcomprising 10GbE, EPON, and/or GPON optical data signals. The EPONand/or GPON optical data signals may be received on a GPON/EPONconnector (e.g., GPON/EPON 1218) from PON port 1202.

Egress optical data signal 1225 may be output by WDM 1220 and opticalswitch 1226 may switch egress optical data signal 1225 onto connector1228 or connector 1227 depending on the position of switch 1226. In someembodiments, connector 1228 may be a primary connector and connector1227 may be a secondary connector or a backup connector. Wavelengthmonitoring connector 1230 may connect connector 1228 to a first port ofwavelength-monitoring ports 1237, and wavelength monitoring connector1229 may connect connector 1227 to a second port ofwavelength-monitoring ports 1237. Wavelength-monitoring ports 1237 maymonitor the wavelengths in egress optical data signal 1225 via connector1228 or connector 1227 depending on the position of switch 1226. Egressoptical data signal 1225 may exit headend 1201 either via connector 1228connected to primary fiber 1235, as egress optical data signal 1240, orvia connector 1227 connected to secondary fiber 1236, as egress opticaldata signal 1241, depending on the position of switch 1226. Egressoptical data signal 1225 may be transmitted as, egress optical datasignal 1240, on primary fiber 1235 to a first connector in the field hubor outside plant. Egress optical data signal may be transmitted as,egress optical data signal 1241, on secondary fiber 1236 to a secondconnector in the field hub or outside plant. The field hub or outsideplant may include a MDM with the first connector and the secondconnector.

Variable optical attenuator (VOA) 1231 and VOA 1232 may be used toreduce the power levels of egress optical data signal 1225 or ingressoptical data signal 1224. The power reduction may done by absorption,reflection, diffusion, scattering, deflection, diffraction, anddispersion, of egress optical data signal 1225 or ingress optical datasignal 1224. VOA 1231 and VOA 1232 typically have a working wavelengthrange in which they absorb all light energy equally. In some embodimentsVOA 1231 and VOA 1232 utilize a length of high-loss optical fiber, thatoperates upon its input optical signal power level in such a way thatits output signal power level is less than the input level. For example,egress optical data signal 1225 may have an input power level to VOA1231 that may be greater than the output power level of egress opticaldata signal 1240 as it is output from VOA 1231. Similarly if egressoptical data signal 1225 is transmitted on connector 1227, egressoptical data signal 1225 may have an input power level to VOA 1232 thatmay be greater than the output power level of egress optical data signal1241. In some embodiments, the output power level of egress optical datasignal 1240 may be greater than the output power level of egress opticaldata signal 1241, and vice versa. The difference in output power levelsbetween egress optical data signal 1240 and egress optical data signal1241 may depend on the mode of primary fiber 1235 and secondary fiber1236. VOA 1232 may have a similar functionality to that have VOA 1231.

The variability of the output power level of VOA 1231 and VOA 1232 maybe achieved using a fiber coupler, where some of the power is not sentto the port that outputs, but to another port. Another possibility is toexploit variable coupling losses, which are influenced by variablepositioning of a fiber end. For example, the transverse position of theoutput fiber or the width of an air gap between two fibers may bevaried, obtaining a variable loss without a strong wavelengthdependence. This principle may be used for single-mode fibers. VOA 1231and VOA 1232 may be based on some piece of doped fiber, exhibitingabsorption within a certain wavelength range.

The operation of headend 1201 may be described by way of the processingof upstream optical data signals received at headend 1201 from a fieldhub or outside plant. For instance, a multi-wavelength ingress opticaldata signal, comprising one or more of a 10GbE optical data signal, EPONoptical data signal, and/or GPON optical data signal, may be an upstreamoptical data signal received on primary fiber 1235 or secondary fiber1236 depending on the position of switch 1226.

Because the multi-wavelength ingress optical data signal is routed toport 1223 of WDM 1220, and is altered negligibly between connector 1228and port 1223 or connector 1227 and port 1223, depending on the positionof switch 1226, the multi-wavelength ingress optical data signal may besubstantially the same as ingress optical data signal 1224. Themulti-wavelength ingress optical data signal may traverse connector 1228and switch 1226, before entering WDM 1220 via port 1223 if switch 1226is connected to connector 1228. The multi-wavelength ingress opticaldata signal may traverse connector 1227 and switch 1226, before enteringWDM 1220 via port 1223 if switch 1226 is connected to connector 1227.WDM 1220 may demultiplex one or more 10GbE optical data signals, EPONoptical data signals, and/or GPON optical data signals from ingressoptical data signal 1224. WDM 1220 may transmit the one or more EPONand/or GPON optical data signals along GPON/EPON 1218 to PON connector1202 via port 1219. WDM 1220 may transmit the one or more 10GbE opticaldata signals (e.g., 10GbE UP 1222) out of port 1221 to OPA 1214.

The one or more 10GbE optical data signals 10GbE UP 1222 may be receivedby OPA 1214. The one or more optical data signals 10GbE UP 1222 maycomprise 10GbE optical data signals. A gain associated OPA 1214 may bebased at least in part on a distance that 10GbE optical data signalshave to travel, similar to that of BOA 1215. The one or more opticaldata signals 10GbE UP 1222 may be amplified by OPA 1214, and OPA 1214may output multi-wavelength upstream optical data signal 1212 to WDM1210.

WDM 1210 may receive the multi-wavelength upstream optical data signal1212 on port 1209 of WDM 1210, and may output one or more optical datasignals 10GbE UP 1207 to DWDM 1205. The one or more optical data signals10GbE UP 1207 are substantially the same as multi-wavelength upstreamoptical data signal 1212. WDM 1210 may function as a circulator whenreceiving multi-wavelength upstream optical data signal 1212 on port1209 and outputting the one or more optical data signals 10GbE UP 1207on port 1208. The one or more optical data signals 10GbE UP 1207 may bereceived by DWDM 1205.

The one or more optical data signals 10GbE UP 1207 may comprise 10GbEoptical data signals. DWDM 1205 may demultiplex the one or more opticaldata signals 10GbE UP 1207 into individual optical data signals inaccordance with the individual wavelengths of the one or more opticaldata signals 10GbE UP 1207. More specifically, the one or more opticaldata signals 10GbE UP 1207 may be demultiplexed into twenty 10GbEoptical data signals, each of which may have a unique wavelength. DWDM1205 may output each of the twenty 10GbE optical data signals to each ofthe transponders of 20×10GbE UP 1204. Each of the transponders of20×10GbE UP 1204 may convert a received corresponding 10GbE optical datasignal, of the 10GbE optical data signals, into a correspondingelectrical signal. More specifically, a first transceiver in each of thetransponders may convert each of the twenty 10GbE optical data signalsinto the corresponding electrical signal. Each of the transponders mayalso comprise a second transceiver that may convert the correspondingelectrical signal into a SONET/SDH optical data signal with acorresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 1204 may transmitthe twenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

FIG. 13 depicts an access network diagram of an OCML headend comprisingWDMs, a DWDM, optical amplifiers, and dispersion control modules (DCMs),in accordance with the disclosure. FIG. 13 shows a schematic of an OCMLheadend according to at least one embodiment of the disclosure. As shownin FIG. 13, headend 1301 is a smart integrated OCML headend, which is acircuit, comprising a DWDM (e.g., DWDM 1305), a first WDM (e.g., WDM1313), a second WDM (e.g., WDM 1319), a third WDM (e.g., WDM 1323), aGPON/EPON connector (e.g., GPON/EPON 1324), a booster amplifier BOA(e.g., BOA 1316), an optical pre-amplifier (OPA) (e.g., OPA 1342), avariable optical attenuator (VOA) (e.g., VOA 1321), an optical switch1326 to feed a primary optical fiber (e.g., Primary Fiber 1330) orsecondary (backup) optical fiber (e.g., Secondary Fiber 1331), and adispersion control module (DCM) (e.g., DCM 1308). DWDM 1305 may besimilar in functionality to DWDM 106 and WDM 1313, WDM 1319, and WDM1323 may be similar in functionality to WDM 108. The disclosure providesa method of transporting multiple 10GbE and GPON/EPON signals on thesame optical fiber over extended links of up to 60 kms without a cablecompany having to put optical amplifiers between the cable's MasterTerminal Center (MTC) facility and a field hub or outside plant. The MTCfacility may be an inside plant facility where a cable company acquiresand combines services to be offered to customers. The MTC facilityprovides these combined services to customers, by transmitting andreceiving optical signals over a plurality of optical fibers to a fieldhub or outside plant which connects the plurality of optical fibers to acustomer's premise. The OCML headend may be located in a secondaryterminal center (STC) that connects the MTC facility to a field hub oroutside plant housing a multiplexer-demultiplexer (MDM) (e.g., MDM 208in FIG. 2).

The EPON signals may operate with the same optical frequencies as GPONand time division multiple access (TDMA). The raw line data rate is 1.25Gbits/s in both the downstream and upstream directions. EPON is fullycompatible with other Ethernet standards, so no conversion orencapsulation is necessary when connecting to Ethernet-based networks oneither end. The same Ethernet frame is used with a payload of up to 1518bytes. EPON may not use a carrier sense multiple access (CSMA)/collisiondetection (CD) access method used in other versions of Ethernet. Thereis a 10-Gbit/s Ethernet version designated as 802.3ay. The line rate maybe 10.3125 Gbits/s. The primary mode is 10 Gbits/s upstream as well asdownstream. A variation uses 10 Gbits/s downstream and 1 Gbit/supstream. The 10-Gbit/s versions use different optical wavelengths onthe fiber, 1575 to 1591 nm downstream and 1260 to 1280 nm upstream sothe 10-Gbit/s system can be wavelength multiplexed on the same fiber asa standard 1-Gbit/s system.

In one aspect, headend 1301 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 1303) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 1304). 20×10GbE DS 1303 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 1304 mayreceive upstream data over 10GbE wavelengths. 20×10GbE DS 1303 maycomprise the same elements and perform the same operations as 20×GbE DS190, and 20×10GbE UP 1304 may comprise the same elements and perform thesame operations as 20×GbE UP 188.

The operation of headend 1301 may be described by way of the processingof downstream optical data signals transmitted from headend 1301 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. Each of thetransponders of 20×10GbE DS 1303 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 1303 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 1303 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 1305 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 1307) comprising the twenty correspondingsecond optical data signals onto a fiber. The multi-wavelengthdownstream optical data signal 10GbE DS 1307 may be a 10GbE optical datasignal. More specifically, DWDM 1305 may multiplex the twentycorresponding second optical data signals onto the fiber, wherein thetwenty multiplexed corresponding second optical data signals compose themulti-wavelength downstream optical data signal. The multi-wavelengthoptical data signal may have a wavelength comprising the twentywavelengths of the twenty corresponding second optical data signals.

The multi-wavelength downstream optical data signal 10GbE DS 1307, maybe input to DCM 1308. 10GbE DS 1307 may be input into DCM 1308 tocompensate for dispersion that 10GbE DS 1307 may experience after beingamplified by BOA 1316 and multiplexed by WDM 1323, with other opticaldata signals, that are downstream from the DCM. The amplified andmultiplexed optical data signal may be referred to as an egress opticaldata signal, as it is the optical data signal that may be transmittedout of headend 1301 over a fiber connecting headend 1301 to a field hubor outside plant. In some embodiments, DCM 1308 may be configured tobalance positive and/or negative dispersion that may be introduced tothe egress optical data signal by the fiber. In some embodiments, DCM1308 may be configured to compensate for positive (temporal broadeningof the egress optical data signal) and/or negative (temporal contractionof the egress optical data signal) dispersion introduced by fiber thatis 80 km or greater in length, to reduce the sensitivity or OSNR levelsof a transceiver in a DWDM located at a field hub or outside plant. Morespecifically, DCM 1308 may be configured to reduce the sensitivity orOSNR level requirement in a photodetector or fiber-optic sensor in thetransceiver, which may drastically reduce the cost of the transceiversused in the DWDM located at the field hub or outside plant. DCM 1308 mayoutput a dispersion controlled version of 10GbE DS 1307 as 10GbE DS1310.

WDM 1313 may be a three port circulator, that receives multi-wavelengthdownstream optical data signal 10GbE DS 1310 on port 1311, and outputsmulti-wavelength downstream optical data signal 10GbE DS 1310, on port1314 as multi-wavelength downstream optical data signal 10GbE DS 1315 toBOA 1316.

BOA 1316 may have a gain that is based at least in part on a distancethat a downstream signal has to travel. For example, the gain may be afunction of a fiber attenuation coefficient α, which is a measure of theintensity of the attenuation of a beam of light as it traverses a lengthof an optical fiber segment. The unit of measurement of the fiberattenuation coefficient is decibels (dB) per km (dB/km). For instance,BOA 1316 may be adjusted based at least in part on the attenuationcoefficient and length of fiber that the egress optical data signal willtravel. More specifically, the gain BOA 1316 may be G=e^((2αL)), where αis the fiber attenuation coefficient, as explained above, and L is thelength of the fiber (e.g., the length of primary fiber 1330 and/or thelength of secondary fiber 1331). Multi-wavelength downstream opticaldata signal 10GbE DS 1315 may be amplified by BOA 1316, and BOA 1316 mayoutput multi-wavelength downstream optical data signal 10GbE DS 1317 toport 1318 of WDM 1319. WDM 1319 outputs a multi-wavelength downstreamoptical data signal (e.g., multi-wavelength downstream optical datasignal 10GbE DS 1340) from port 1320, which may be substantially thesame as multi-wavelength downstream optical data signal 10GbE DS 1317.Multi-wavelength downstream optical data signal 10GbE DS 1340 may beinput to variable optical amplifier (VOA) 1321.

VOA 1321 may be used to reduce the power levels of Multi-wavelengthdownstream optical data signal 10GbE DS 1340. The power reduction maydone by absorption, reflection, diffusion, scattering, deflection,diffraction, and dispersion, of Multi-wavelength downstream optical datasignal 10GbE DS 1340. VOA 1321 typically have a working wavelength rangein which they absorb all light energy equally. In some embodiments VOA1321 utilize a length of high-loss optical fiber, that operates upon itsinput optical signal power level in such a way that its output signalpower level is less than the input level. For example, multi-wavelengthdownstream optical data signal 10GbE DS 1340 may have an input powerlevel to VOA 1321 that may be greater than the output power level ofmulti-wavelength downstream optical data signal 10GbE DS 1339.

The variability of the output power level of VOA 1321 may be achievedusing a fiber coupler, where some of the power is not sent to the portthat outputs, but to another port. Another possibility is to exploitvariable coupling losses, which are influenced by variable positioningof a fiber end. For example, the transverse position of the output fiberor the width of an air gap between two fibers may be varied, obtaining avariable loss without a strong wavelength dependence. This principle maybe used for single-mode fibers. VOA 13211 may be based on some piece ofdoped fiber, exhibiting absorption within a certain wavelength range.

WDM 1323 may multiplex multi-wavelength downstream optical data signal10GbE DS 1339 and one or more EPON, and/or GPON optical data signals.The EPON and/or GPON optical data signals may be received on a GPON/EPONconnector (e.g., GPON/EPON 1324) from PON port 1302. The resultingmultiplexed optical data signal may be referred to as egress opticaldata signal 1335.

Egress optical data signal 1335 may be output by WDM 1323 and opticalswitch 1326 may switch egress optical data signal 1335 onto connector1327 or connector 1334 depending on the position of switch 1326. In someembodiments, connector 1327 may be a primary connector and connector1334 may be a secondary connector or a backup connector. Wavelengthmonitoring connector 1328 may connect connector 1327 to a first port ofwavelength-monitoring ports 1344, and wavelength monitoring connector1333 may connect connector 1334 to a second port ofwavelength-monitoring ports 1344. Wavelength-monitoring ports 1344 maymonitor the wavelengths in egress optical data signal 1335 via connector1327 or connector 1334 depending on the position of switch 1326. Egressoptical data signal 1335 may exit headend 1301 via connector 1327connected to primary fiber 1330, and may be received on a firstconnector in the field hub or outside plant. Egress optical data signal1335 may exit headend 1301 via connector 1334 connected to secondaryfiber 1331, and may be received on a second connector in the field hubor outside plant. The field hub or outside plant may include a MDM withthe first connector and the second connector.

The operation of headend 1301 may be described by way of the processingof upstream optical data signals received at headend 1301 from a fieldhub or outside plant. For instance, a multi-wavelength ingress opticaldata signal, comprising one or more of a 10GbE optical data signal, EPONoptical data signal, and/or GPON optical data signal or a 10GEPN.XGPONmay be an upstream optical data signal received on primary fiber 1330 orsecondary fiber 1331 depending on the position of switch 1326.

Multi-wavelength ingress optical data signal 1336 may traverse connector1327 and switch 1326, before entering WDM 1323 via port 1337 if switch1326 is connected to connector 1327. Multi-wavelength ingress opticaldata signal 1336 may traverse connector 1334 and switch 1326, beforeentering WDM 1323 via port 1337 if switch 1326 is connected to connector1327. WDM 1323 may demultiplex one or more 10GbE optical data signals,EPON optical data signals, and/or GPON optical data signals frommulti-wavelength ingress optical data signal 1336. WDM 1323 may transmitthe one or more EPON and/or GPON optical data signals along GPON/EPON1324 to PON connector 1302 via port 1325. WDM 1323 may transmit the oneor more 10GbE optical data signals (e.g., 10GbE UP 1341) out of port1338 to OPA 1342.

The one or more 10GbE optical data signals 10GbE UP 1341 may be receivedby OPA 1342. The one or more optical data signals 10GbE UP 1341 maycomprise 10GbE optical data signals. A gain associated OPA 1342 may bebased at least in part on a distance that 10GbE optical data signalshave to travel, similar to that of BOA 1316. The one or more opticaldata signals 10GbE UP 1341 may be amplified by OPA 1342, and OPA 1342may output multi-wavelength upstream optical data signal 1343 to WDM1313.

WDM 1313 may receive the multi-wavelength upstream optical data signal1343 on port 1312, and may output one or more optical data signals 10GbEUP 1309 to DCM 1308. DCM 1308 may perform one or more operations on oneor more optical data signals 10GbE UP 1309 to compensate for anydispersion that may have been introduced by circuit components (e.g.,WDM 1313, OPA 1342, or WDM 1323) or imperfections or issues with anoptical fiber (e.g., primary fiber 1330 or secondary fiber 1331). DCM1308 may output one or more optical data signals 10GbE UP 1306 to DWDM1305. The one or more optical data signals 10GbE UP 1309 aresubstantially the same as multi-wavelength upstream optical data signal1343. WDM 1313 may function as a circulator when receivingmulti-wavelength upstream optical data signal 1343 on port 1312. The oneor more optical data signals 10GbE UP 1306 may be received by DWDM 1305.

The one or more optical data signals 10GbE UP 1306 may comprise 10GbEoptical data signals. DWDM 1305 may demultiplex the one or more opticaldata signals 10GbE UP 1306 into individual optical data signals inaccordance with the individual wavelengths of the one or more opticaldata signals 10GbE UP 1306. More specifically, the one or more opticaldata signals 10GbE UP 1306 may be demultiplexed into twenty 10GbEoptical data signals, each of which may have a unique wavelength. DWDM1305 may output each of the twenty 10GbE optical data signals to each ofthe transponders of 20×10GbE UP 1304. Each of the transponders of20×10GbE UP 1304 may convert a received corresponding 10GbE optical datasignal, of the 10GbE optical data signals, into a correspondingelectrical signal. More specifically, a first transceiver in each of thetransponders may convert each of the twenty 10GbE optical data signalsinto the corresponding electrical signal. Each of the transponders mayalso comprise a second transceiver that may convert the correspondingelectrical signal into a SONET/SDH optical data signal with acorresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 1304 may transmitthe twenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

FIG. 14 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure. FIG. 14 shows a schematic ofan OCML headend according to at least one embodiment of the disclosure.As shown in FIG. 14, headend 1401 is a smart integrated OCML headend,which is a circuit, comprising a DWDM (e.g., DWDM 1405), a first WDM(e.g., WDM 1410), a second WDM (e.g., WDM 1418), a first DCM (e.g., DCM1413), a second DCM 1438, a GPON/EPON connector (e.g., GPON/EPON 1420),a booster amplifier BOA (e.g., BOA 1415), an optical pre-amplifier (OPA)(e.g., OPA 1436), a first variable optical attenuator (VOA) (e.g., VOA1424), a second VOA (e.g., VOA 1429), and an optical switch 1421 to feeda primary optical fiber (e.g., Primary Fiber 1426) or secondary (backup)optical fiber (e.g., Secondary Fiber 1427). DWDM 1405 may be similar infunctionality to DWDM 106 and WDM 1410 and WDM 1418 may be similar infunctionality to WDM 108. DCM 1413 and DCM 1438 may be similar infunctionality to DCM 112. The disclosure provides a method oftransporting multiple 10GbE and GPON/EPON signals on the same opticalfiber over extended links of up to 60 kms without a cable company havingto put optical amplifiers between the cable's Master Terminal Center(MTC) facility and a field hub or outside plant. The MTC facility may bean inside plant facility where a cable company acquires and combinesservices to be offered to customers. The MTC facility provides thesecombined services to customers, by transmitting and receiving opticalsignals over a plurality of optical fibers to a field hub or outsideplant which connects the plurality of optical fibers to a customer'spremise. The OCML headend may be located in a secondary terminal center(STC) that connects the MTC facility to a field hub or outside planthousing a multiplexer-demultiplexer (MDM) (e.g., MDM 208 in FIG. 2).

The EPON signals may operate with the same optical frequencies as GPONand time division multiple access (TDMA). The raw line data rate is 1.25Gbits/s in both the downstream and upstream directions. EPON is fullycompatible with other Ethernet standards, so no conversion orencapsulation is necessary when connecting to Ethernet-based networks oneither end. The same Ethernet frame is used with a payload of up to 1518bytes. EPON may not use a carrier sense multiple access (CSMA)/collisiondetection (CD) access method used in other versions of Ethernet. Thereis a 10-Gbit/s Ethernet version designated as 802.3ay. The line rate maybe 10.3125 Gbits/s. The primary mode is 10 Gbits/s upstream as well asdownstream. A variation uses 10 Gbits/s downstream and 1 Gbit/supstream. The 10-Gbit/s versions use different optical wavelengths onthe fiber, 1571 to 1591 nm downstream and 1260 to 1280 nm upstream sothe 10-Gbit/s system can be wavelength multiplexed on the same fiber asa standard 1-Gbit/s system.

In one aspect, headend 1401 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 1403) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 1404). 20×10GbE DS 1403 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 1404 mayreceive upstream data over 10GbE wavelengths. 20×10GbE DS 1403 maycomprise the same elements and perform the same operations as 20×GbE DS190, and 20×10GbE UP 1404 may comprise the same elements and perform thesame operations as 20×GbE UP 188.

The operation of headend 1401 may be described by way of the processingof downstream optical data signals transmitted from headend 1401 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. Each of thetransponders of 20×10GbE DS 1403 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 1403 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 1403 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 1405 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 1407) comprising the twenty correspondingsecond optical data signals onto a fiber. The multi-wavelengthdownstream optical data signal 10GbE DS 1407 may be a 10GbE optical datasignal. More specifically, DWDM 1405 may multiplex the twentycorresponding second optical data signals onto the fiber, wherein thetwenty multiplexed corresponding second optical data signals compose themulti-wavelength downstream optical data signal. The multi-wavelengthoptical data signal may have a wavelength comprising the twentywavelengths of the twenty corresponding second optical data signals.

The multi-wavelength downstream optical data signal 10GbE DS 1407, maybe input to WDM 1410. WDM 1410 may be a three port circulator, thatreceives multi-wavelength downstream optical data signal 10GbE DS 1407on port 1408, and outputs multi-wavelength downstream optical datasignal 10GbE DS 1407, on port 1408 as multi-wavelength downstreamoptical data signal 10GbE DS 1412 on port 1411 to DCM 1413.

Multi-wavelength downstream optical data signal 10GbE DS 1412 may beinput into DCM 1413 to compensate for dispersion that 10GbE DS 1412 mayexperience after being amplified by BOA 1415 and multiplexed by WDM1428, with other optical data signals, that are downstream from DCM1431. The amplified and multiplexed optical data signal may be referredto as an egress optical data signal, as it is the optical data signalthat may be transmitted out of headend 1401 over a fiber connectingheadend 1401 to a field hub or outside plant. In some embodiments, DCM1413 may be configured to balance positive and/or negative dispersionthat may be introduced to the egress optical data signal by the fiber.In some embodiments, DCM 1413 may be configured to compensate forpositive (temporal broadening of the egress optical data signal) and/ornegative (temporal contraction of the egress optical data signal)dispersion introduced by fiber that is 80 km or greater in length, toreduce the sensitivity or OSNR levels of a transceiver in a DWDM locatedat a field hub or outside plant. More specifically, DCM 1413 may beconfigured to reduce the sensitivity or OSNR level requirement in aphotodetector or fiber-optic sensor in the transceiver, which maydrastically reduce the cost of the transceivers used in the DWDM locatedat the field hub or outside plant. DCM 1413 may output a dispersioncontrolled version of 10GbE DS 1412 as 10GbE DS 1414.

BOA 1415 may have a gain that is based at least in part on a distancethat a downstream signal has to travel. For example, the gain may be afunction of a fiber attenuation coefficient α, which is a measure of theintensity of the attenuation of a beam of light as it traverses a lengthof an optical fiber segment. The unit of measurement of the fiberattenuation coefficient is decibels (dB) per km (dB/km). For instance,BOA 1415 may be adjusted based at least in part on the attenuationcoefficient and length of fiber that the egress optical data signal willtravel. More specifically, the gain BOA 1415 may be G=e^((2αL)), where αis the fiber attenuation coefficient, as explained above, and L is thelength of the fiber (e.g., the length of primary fiber 1426 and/or thelength of secondary fiber 1427). Multi-wavelength downstream opticaldata signal 10GbE DS 1414 may be amplified by BOA 1415, and BOA 1415 mayoutput multi-wavelength downstream optical data signal 10GbE DS 11416 toport 1417 of WDM 1418.

WDM 1418 may multiplex multi-wavelength downstream optical data signal10GbE DS 1416 and one or more EPON, and/or GPON optical data signals.The EPON and/or GPON optical data signals may be received on a GPON/EPONconnector (e.g., GPON/EPON 1420) from PON port 1402. The resultingmultiplexed optical data signal may be referred to as egress opticaldata signal 1432.

Egress optical data signal 1432 may be output by WDM 1418 and opticalswitch 1421 may switch egress optical data signal 1432 onto connector1422 or connector 1431 depending on the position of switch 1421. In someembodiments, connector 1422 may be a primary connector and connector1431 may be a secondary connector or a backup connector. Wavelengthmonitoring connector 1423 may connect connector 1422 to a first port ofwavelength-monitoring ports 1440, and wavelength monitoring connector1430 may connect connector 1431 to a second port ofwavelength-monitoring ports 1440. Wavelength-monitoring ports 1440 maymonitor the wavelengths in egress optical data signal 1432 via connector1422 or connector 1431 depending on the position of switch 1421. Egressoptical data signal 1432 may exit headend 1401 either via connector 1422connected to primary fiber 1426, as egress optical data signal 1441, orvia connector 1431 connected to secondary fiber 1427, as egress opticaldata signal 1442, depending on the position of switch 1421. Egressoptical data signal 1432 may be transmitted as, egress optical datasignal 1441, on primary fiber 1426 to a first connector in the field hubor outside plant. Egress optical data signal may be transmitted as,egress optical data signal 1442, on secondary fiber 1427 to a secondconnector in the field hub or outside plant. The field hub or outsideplant may include a MDM with the first connector and the secondconnector.

Variable optical attenuator (VOA) 1424 and VOA 1429 may be used toreduce the power levels of egress optical data signal 1432 or ingressoptical data signal 1433. The power reduction may done by absorption,reflection, diffusion, scattering, deflection, diffraction, anddispersion, of egress optical data signal 1432 or ingress optical datasignal 1433. VOA 1424 and VOA 1429 typically have a working wavelengthrange in which they absorb all light energy equally. In some embodimentsVOA 1424 and VOA 1429 utilize a length of high-loss optical fiber, thatoperates upon its input optical signal power level in such a way thatits output signal power level is less than the input level. For example,egress optical data signal 1432 may have an input power level to VOA1424 that may be greater than the output power level of egress opticaldata signal 1441 as it is output from VOA 1424. Similarly if egressoptical data signal 1432 is transmitted on connector 1431, egressoptical data signal 1432 may have an input power level to VOA 1429 thatmay be greater than the output power level of egress optical data signal1442. In some embodiments, the output power level of egress optical datasignal 1441 may be greater than the output power level of egress opticaldata signal 1442, and vice versa. The difference in output power levelsbetween egress optical data signal 1441 and egress optical data signal1442 may depend on the mode of primary fiber 1426 and secondary fiber1427. VOA 1424 may have a similar functionality to that have VOA 1429.

The variability of the output power level of VOA 1424 and VOA 1429 maybe achieved using a fiber coupler, where some of the power is not sentto the port that outputs, but to another port. Another possibility is toexploit variable coupling losses, which are influenced by variablepositioning of a fiber end. For example, the transverse position of theoutput fiber or the width of an air gap between two fibers may bevaried, obtaining a variable loss without a strong wavelengthdependence. This principle may be used for single-mode fibers. VOA 1424and VOA 1429 may be based on some piece of doped fiber, exhibitingabsorption within a certain wavelength range.

The operation of headend 1401 may be described by way of the processingof upstream optical data signals received at headend 1401 from a fieldhub or outside plant. For instance, a multi-wavelength ingress opticaldata signal, comprising one or more of a 10GbE optical data signal, EPONoptical data signal, and/or GPON optical data signal, may be an upstreamoptical data signal received on primary fiber 1426 or secondary fiber1427 depending on the position of switch 1421.

Because the multi-wavelength ingress optical data signal is routed toport 1434 of WDM 1418, and is altered negligibly between connector 1422and port 1434 or connector 1432 and port 1434, depending on the positionof switch 1421, the multi-wavelength ingress optical data signal may besubstantially the same as ingress optical data signal 1433. Themulti-wavelength ingress optical data signal may traverse connector 1422and switch 1421, before entering WDM 1418 via port 1434 if switch 1421is connected to connector 1422. The multi-wavelength ingress opticaldata signal may traverse connector 1431 and switch 1421, before enteringWDM 1418 via port 1434 if switch 1421 is connected to connector 1431.WDM 1418 may demultiplex one or more 10GbE optical data signals, EPONoptical data signals, and/or GPON optical data signals from ingressoptical data signal 1433. WDM 1418 may transmit the one or more EPONand/or GPON optical data signals along GPON/EPON 11420 to PON connector1402 via port 1419. WDM 1418 may transmit the one or more 10GbE opticaldata signals (e.g., 10GbE UP 1435) out of port 1421 to OPA 1436.

The one or more 10GbE optical data signals 10GbE UP 1435 may be receivedby OPA 1436. The one or more optical data signals 10GbE UP 1435 maycomprise 10GbE optical data signals. A gain associated OPA 1436 may bebased at least in part on a distance that 10GbE optical data signalshave to travel, similar to that of BOA 1415. The one or more opticaldata signals 10GbE UP 1435 may be amplified by OPA 1436, and OPA 1436may output multi-wavelength upstream optical data signal 1437 to DCM1438.

In some embodiments, DCM 1438 may be configured to balance positiveand/or negative dispersion that may be introduced to a SONET/SDH egressoptical data signal that may enter headend 1401 from 20×10GbE UP 1404.The SONET/SDH egress optical data signal may be an upstream signal froma field hub or outside plant destined for a MTC. For example, a customerpremise may be connected to the field hub or outside plant and may sendone or more packets via a SONET/SDH network to the field hub or outsideplant which may in turn transmit the one or more packets using 10GbEoptical data signals to headend 1401. The one or more packets may bedestined for a company web server connected to the MTC via a backbonenetwork. Because headend 1401 may be collocated in a STC that isconnected to the MTC via an optical ring network, wherein the connectionbetween the STC and MTC is an SONET/SDH optical network connection, DCM1438 may be configured to compensate for positive and/or negativedispersion on the SONET/SDH optical network connection. That is DCM 1438may be configured to reduce temporal broadening of the SONET/SDH egressoptical data signal or temporal contraction of the SONET/SDH egressoptical data signal. DCM 1438 may input 10GbE UP 1437 and my output10GbE UP 1439 to WDM 1410.

WDM 1410 may receive the multi-wavelength upstream optical data signal10GbE UP 1439 on port 1409 of WDM 1410, and may output one or moreoptical data signals 10GbE UP 1206 to DWDM 1405. The one or more opticaldata signals 10GbE UP 1406 are substantially the same asmulti-wavelength upstream optical data signal 10GbE UP 1439. WDM 1410may function as a circulator when receiving multi-wavelength upstreamoptical data signal 10GbE UP 1439 on port 1409 and may output the one ormore optical data signals 10GbE UP 1406 on port 1408. The one or moreoptical data signals 10GbE UP 1406 may be received by DWDM 1405.

The one or more optical data signals 10GbE UP 1406 may comprise 10GbEoptical data signals. DWDM 1405 may demultiplex the one or more opticaldata signals 10GbE UP 1406 into individual optical data signals inaccordance with the individual wavelengths of the one or more opticaldata signals 10GbE UP 1406. More specifically, the one or more opticaldata signals 10GbE UP 1406 may be demultiplexed into twenty 10GbEoptical data signals, each of which may have a unique wavelength. DWDM1405 may output each of the twenty 10GbE optical data signals to each ofthe transponders of 20×10GbE UP 1404. Each of the transponders of20×10GbE UP 1404 may convert a received corresponding 10GbE optical datasignal, of the 10GbE optical data signals, into a correspondingelectrical signal. More specifically, a first transceiver in each of thetransponders may convert each of the twenty 10GbE optical data signalsinto the corresponding electrical signal. Each of the transponders mayalso comprise a second transceiver that may convert the correspondingelectrical signal into a SONET/SDH optical data signal with acorresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 1404 may transmitthe twenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

FIG. 15 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure. FIG. 15 shows a schematic ofan OCML headend according to at least one embodiment of the disclosure.As shown in FIG. 15, headend 1501 is a smart integrated OCML headend,which is a circuit, comprising a DWDM (e.g., DWDM 1506), a first WDM(e.g., WDM 1513), a second WDM (e.g., WDM 1524), a GPON/EPON connector(e.g., GPON/EPON 1528), a booster amplifier BOA (e.g., BOA 1516), anoptical pre-amplifier (OPA) (e.g., OPA 1544), an optical switch 1530 tofeed a primary optical fiber (e.g., Primary Fiber 1550) or secondary(backup) optical fiber (e.g., Secondary Fiber 1551). DWDM 1506 may besimilar in functionality to DWDM 106 and WDM 1513 and WDM 1544 may besimilar in functionality to WDM 108. The disclosure provides a method oftransporting multiple 10GbE and GPON/EPON signals on the same opticalfiber over extended links of up to 60 kms without a cable company havingto put optical amplifiers between the cable's Master Terminal Center(MTC) facility and a field hub or outside plant. The MTC facility may bean inside plant facility where a cable company acquires and combinesservices to be offered to customers. The MTC facility provides thesecombined services to customers, by transmitting and receiving opticalsignals over a plurality of optical fibers to a field hub or outsideplant which connects the plurality of optical fibers to a customer'spremise. The OCML headend may be located in the MTC facility. A fieldhub or outside plant may house a multiplexer-demultiplexer (MDM) (e.g.,MDM 1591).

The EPON signals may operate with the same optical frequencies as GPONand time division multiple access (TDMA). The raw line data rate is 1.25Gbits/s in both the downstream and upstream directions.

EPON is fully compatible with other Ethernet standards, so no conversionor encapsulation is necessary when connecting to Ethernet-based networkson either end. The same Ethernet frame is used with a payload of up to1518 bytes. EPON may not use a carrier sense multiple access(CSMA)/collision detection (CD) access method used in other versions ofEthernet.

There is a 10-Gbit/s Ethernet version designated as 802.3ay. The linerate may be 10.3125 Gbits/s. The primary mode is 10 Gbits/s upstream aswell as downstream. A variation uses 10 Gbits/s downstream and 1 Gbit/supstream. The 10-Gbit/s versions use different optical wavelengths onthe fiber, 1571 to 1591 nm downstream and 1260 to 1280 nm upstream sothe 10-Gbit/s system can be wavelength multiplexed on the same fiber asa standard 1-Gbit/s system.

In one aspect, headend 1501 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 1503) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 1504). 20×10GbE DS 1503 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 1504 mayreceive upstream data over 10GbE wavelengths. 20×10GbE DS 1503 maycomprise the same elements and perform the same operations as 20×GbE DS190, and 20×10GbE UP 1504 may comprise the same elements and perform thesame operations as 20×GbE UP 188.

The operation of headend 1501 may be described by way of the processingof downstream optical data signals transmitted from headend 1501 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. Each of thetransponders of 20×10GbE DS 1503 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 1503 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 1503 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 1506 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 1508) comprising the twenty correspondingsecond optical data signals onto a fiber. The multi-wavelengthdownstream optical data signal 10GbE DS 1508 may be a 10GbE optical datasignal. More specifically, DWDM 1506 may multiplex the twentycorresponding second optical data signals onto the fiber, wherein thetwenty multiplexed corresponding second optical data signals compose themulti-wavelength downstream optical data signal. The multi-wavelengthoptical data signal may have a wavelength comprising the twentywavelengths of the twenty corresponding second optical data signals.

The multi-wavelength downstream optical data signal 10GbE DS 1508, maybe input to WDM 1513. WDM 1513 may be a three port circulator, thatreceives multi-wavelength downstream optical data signal 10GbE DS 1508on port 1509, and outputs multi-wavelength downstream optical datasignal 10GbE DS 1515, on port 1514 as multi-wavelength downstreamoptical data signal 10GbE DS 1515 to BOA 1516.

BOA 1516 may have a gain that is based at least in part on a distancethat a downstream signal has to travel. For example, the gain may be afunction of a fiber attenuation coefficient α, which is a measure of theintensity of the attenuation of a beam of light as it traverses a lengthof an optical fiber segment. The unit of measurement of the fiberattenuation coefficient is decibels (dB) per km (dB/km). For instance,BOA 1516 may be adjusted based at least in part on the attenuationcoefficient and length of fiber that the egress optical data signal willtravel. More specifically, the gain BOA 1516 may be G=e^((2αL)), where αis the fiber attenuation coefficient, as explained above, and L is thelength of the fiber (e.g., the length of primary fiber 1550 and/or thelength of secondary fiber 1551). Multi-wavelength downstream opticaldata signal 10GbE DS 1515 may be amplified by BOA 1516, and BOA 1516 mayoutput multi-wavelength downstream optical data signal 10GbE DS 1518 toport 1520 of WDM 1524. WDM 1524 outputs an egress optical data signalfrom port 1541, which may be a multi-wavelength optical data signalcomprising 10GbE, EPON, and/or GPON optical data signals. The EPONand/or GPON optical data signals may be received on a GPON/EPONconnector (e.g., GPON/EPON 1528) from PON port 1502.

Egress optical data signal 1539 may be output by WDM 1524 and opticalswitch 1530 may switch egress optical data signal 1539 onto connector1532 or connector 1538 depending on the position of switch 1530. In someembodiments, connector 1532 may be a primary connector and connector1538 may be a secondary connector or a backup connector. Wavelengthmonitoring connector 1534 may connect connector 1532 to a first port ofwavelength-monitoring ports 1548, and wavelength monitoring connector1537 may connect connector 1538 to a second port ofwavelength-monitoring ports 1548. Wavelength-monitoring ports 1548 maymonitor the wavelengths in egress optical data signal 1539 via connector1532 or connector 1538 depending on the position of switch 1530. Egressoptical data signal 1530 may exit headend 1501 either via connector 1532connected to primary fiber 1550, or via connector 1538 connected tosecondary fiber 1551, depending on the position of switch 1530. Egressoptical data signal 1539 may be transmitted on primary fiber 1550 to anoptical splitter (e.g., the optical splitter 1593) inside of orcollocated with a MDM (e.g., the MDM 1591). Egress optical data signal1539 may be transmitted on secondary fiber 1551 to the optical splitter1593.

Egress optical data signal 1539 may be received at optical splitter 1593as an ingress optical data signal. Optical splitter 1593 may also bereferred to as a beam splitter, and may comprise one or more quartzsubstrates of an integrated waveguide optical power distribution device.Optical splitter 1593 may be a passive optical network device. It may bean optical fiber tandem deice comprising one or more input terminals andone or more output terminals. Optical splitter 1539 may be FusedBiconical Taper (FBT) splitter or Planar Lightwave Circuit (PLC)splitter. Optical splitter 1593 may be a balanced splitter whereinoptical splitter 1593 comprises 2 input fibers and one or more outputfibers over which the ingress optical data signal may be spreadproportionally. In some embodiments, the ingress optical data signal maynot be spread proportionally across the output fibers of opticalsplitter 1593. In some embodiments, optical splitter 1593 may comprise 2input fibers and 2 output fibers. A first input fiber of opticalsplitter 1593 may be connected to primary fiber 1550 and a second inputfiber of optical splitter 1593 may be connected to secondary fiber 1551.

A first output fiber of optical splitter 1593 may be connected to afilter (e.g., C-band block 1592) that filters out packets of light, inthe ingress optical data signal, with wavelengths between 1530 nm and1565 nm. This range of wavelengths may coincide with a C-band ofwavelengths. In some other embodiments, the filter may filter outpackets of light with wavelengths not inclusive of the wavelengthsbetween 1260 nm and 1520 nm and not inclusive of wavelengths between1570 nm and 1660 nm. The packets of light with wavelengths inclusive ofthe wavelengths between 1260 nm and 1520 nm and inclusive of wavelengthsbetween 1570 nm and 1660 nm, may correspond to the wavelengths of thepackets of light carrying the one or more EPON and/or GPON optical datasignals transmitted along GPON/EPON 1528. More specifically, opticalsplitter 1593, may receive one or more downstream EPON and/or GPONoptical data signals 1560, in the ingress optical data signal, thatcorresponds to the one or more EPON and/or GPON optical data signalstransmitted along GPON/EPON 1528. In some embodiments, the one or moredownstream EPON and/or GPON optical data signals 1560 may have the samewavelength as GPON DS 806. Optical splitter 1593 may output the one ormore downstream EPON and/or GPON optical data signals 1560, received inthe ingress optical data signal, to C-band block 1592.

C-band block 1592 may output one or more downstream EPON and/or GPONoptical data signals 1597 corresponding to the one or more downstreamEPON and/or GPON optical data signals 1560 with wavelengths between 1260nm and 1520 nm and wavelengths between 1570 nm and 1660 nm. The C-bandblock 1592 may transmit the one or more downstream EPON and/or GPONoptical data signals 1597 to an express port (not shown in FIG. 15)collocated with, or attached to MDM 1591. In some embodiments, theexpress port may be located within the MDM 1591.

A second output fiber of optical splitter 1593 may be connected tocoupled optical power (COP) 1594. COP 1594 may be a PON device thatmonitors the coupled optical power between Optical Splitter 1593 andDWDM 1596. In some embodiments, the coupled optical power may be apercentage value. For instance, the coupled optical power may be 1%.Optical splitter 1593, may receive one or more downstream 10GbE opticaldata signals, in the ingress optical data signal, that corresponds to10GbE DS 1508. In some embodiments, the one or more downstream 10GbEoptical data signals may have the same wavelength as 10GbE 808. Opticalsplitter 1593 may output the one or more downstream 10GbE optical datasignals 1563, received in the ingress optical data signal, to COP 1594.COP 1594 may output a first percentage of the one or more downstream10GbE optical data signals 1563 to 10GbE upstream and downstream testports (e.g., 10GbE UP & DS Test Ports 1595). The first percentage may bea percentage of the one or more downstream 10GbE optical data signals1563 tested by the 10GbE upstream and downstream test ports. The firstpercentage of the one or more downstream 10GbE optical data signals 1563may be a monitoring signal used by a spectrum analyzer to measureoptical power levels of a specific wavelength. The first percentage ofthe one or more downstream 10GbE optical data signals 1563 may also beused by the spectrum analyzer to analyze certain characteristics of thewavelengths of the first percentage of the one or more downstream 10GbEoptical data signals 1563. COP 1594 may output a second percentage ofthe one or more downstream 10GbE optical data signals 1565 to DWDM 1596.Because the one or more downstream 10GbE optical data signals 1565 maybe a multi-wavelength downstream optical data signal DWDM 1596 maydemultiplex the one or more downstream 10GbE optical data signals 1565into individual optical data signals in accordance with the individualwavelengths of the one or more downstream 10GbE optical data signals1565. More specifically, the one or more downstream 10GbE optical datasignals 1565 may be demultiplexed into twenty 10GbE optical datasignals, each of which may have a unique wavelength. DWDM 1596 mayoutput each of the twenty 10GbE optical data signals to each of thetransponders of 20×10GbE DS 1598. Each of the transponders of 20×10GbEDS 1598 may be in a RPD (not shown) and may convert a receivedcorresponding 10GbE optical data signal, of the 10GbE optical datasignals, into a corresponding electrical signal. More specifically, afirst transceiver in each of the transponders may convert each of thetwenty 10GbE optical data signals into the corresponding electricalsignal. Each of the transponders may also comprise a second transceiverthat may convert the corresponding electrical signal into a SONET/SDHoptical data signal with a corresponding SONET/SDH optical data signalwavelength. In some embodiments, each of the twenty correspondingSONET/SDH optical data signals may have the same wavelength. In otherembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have unique wavelengths. In some embodiments, the RPD may besimilar in functionality to Remote PHY Node 207. The RPD may convert theSONET/SDH optical data signals into an electrical signal that may betransmitted over one or more coaxial cables. MDM 1591 may be similar infunctionality to MDM 208 and may be connected to the RPD in a waysimilar to the connection between MDM 208 and Remote PHY Node 207.

The operation of MDM 1591 may be further described by way of theprocessing of an upstream optical data signal transmitted to headend1501. Each of the transponders of 20×10GbE UP 1599 may receive aSONET/SDH optical data signal and each of the transponders may convertthe SONET/SDH optical data signal into an electrical signal. Each of thetransponders of 20×10GbE UP 1599 may receive the SONET/SDH optical datasignal from the RPD. The RPD may also convert one or more electricalsignals into the SONET/SDH optical data signal.

More specifically, a first transceiver in the transponder may convertthe SONET/SDH optical data signal into an electrical signal. A secondtransceiver may then convert the electrical signal into a second opticaldata signal, wherein the second optical data signal comprises one ormore packets of light each of which may have a distinct wavelength.Because the one or more packets of light each have a distinctwavelength, the second optical data signal may be said to have thisdistinct wavelength. Thus, the twenty transponders in 20×10GbE UP 1599may each receive a SONET/SDH optical data signal, and each of the twentytransponders may convert the received SONET/SDH optical data signal intoa corresponding second optical data signal, wherein each of thecorresponding second optical data signals has a unique wavelength. Thatis, the wavelength of each of the corresponding second optical datasignals is distinguishable from the wavelength of any of the othercorresponding second optical data signals. Thus 20×10GbE UP 1599 maygenerate twenty corresponding second optical data signals each of whichhas a unique wavelength.

DWDM 1596 may receive twenty corresponding second optical data signalsas an input and output a multi-wavelength upstream optical data signal(e.g., multi-wavelength upstream optical data signal 1564) comprisingthe twenty corresponding second optical data signals. Themulti-wavelength upstream optical data signal 1564 may be a 10GbEoptical data signal. More specifically, DWDM 1596 may multiplex thetwenty corresponding second optical data signals onto the fiberconnecting DWDM 1596 and COP 1594, wherein the twenty multiplexedcorresponding second optical data signals compose the multi-wavelengthdownstream optical data signal. The multi-wavelength optical data signalmay have a wavelength comprising the twenty wavelengths of the twentycorresponding second optical data signals.

The multi-wavelength upstream optical data signal 1564, may be input toCOP 1594. COP 1594 may output a first percentage of the multi-wavelengthupstream optical data signal 1564 to 10GbE upstream and downstream testports (e.g., 10GbE UP & DS Test Ports 1695). The first percentage may bea percentage of the multi-wavelength upstream optical data signal 1564tested by the 10GbE upstream and downstream test ports COP 1594 mayoutput a second percentage of the multi-wavelength upstream optical datasignal 1564 to optical splitter 1593 as the multi-wavelength upstreamoptical data signal 1562.

C-band block 1592 may receive one or more upstream EPON and/or GPONoptical data signals 1566 from an express port (not shown in FIG. 15)collocated with, or attached to MDM 1591. In some embodiments, theexpress port may be located within the MDM 1591. C-band block 1592 mayfilter out packets of light, in the one or more upstream EPON and/orGPON optical data signals 1566, with wavelengths between 1530 nm and1565 nm. Thus C-band block 1592 may output one or more upstream EPONand/or GPON optical data signals 1561 with wavelengths between 1260 nmand 1520 nm and wavelengths between 1570 nm and 1660 nm.

Optical splitter 1593 may receive one or more upstream EPON and/or GPONoptical data signals 1561, and may also receive the multi-wavelengthupstream optical data signal 1562, and may multiplex themulti-wavelength one or more upstream EPON and/or GPON optical datasignals 1561 with the multi-wavelength upstream optical data signal1562. Optical splitter 1593 outputs an egress optical data signal, whichmay be a multi-wavelength optical data signal comprising 10GbE,GPON/EPON optical data signals corresponding to the multiplexedmulti-wavelength one or more upstream EPON and/or GPON optical datasignals 1561 and multi-wavelength upstream optical data signal 1562.Optical splitter 1593 may output the egress optical data signal ontoprimary fiber 1550 connecting the optical splitter 1593 to port 1536.Optical splitter 1593 may also output the egress optical data signalonto secondary fiber 1551 connecting the optical splitter 1593 to port1546.

The operation of headend 1501 may be described by way of the processingof upstream optical data signals received at headend 1501 from MDM 1591.For instance, a multi-wavelength ingress optical data signal, comprisingone or more of a 10GbE optical data signal, EPON optical data signal,and/or GPON optical data signal, may be an upstream optical data signalreceived on primary fiber 1550 or secondary fiber 1551 depending on theposition of switch 1530. The upstream optical data signal may besubstantially the same as the egress optical data signal.

The multi-wavelength ingress optical data signal 1540 may traverseconnector 1532 and switch 1530, before entering WDM 1524 via port 1541if switch 1530 is connected to connector 1532. The multi-wavelengthingress optical data signal may traverse connector 1538 and switch 1530,before entering WDM 1524 via port 1541 if switch 1530 is connected toconnector 1538. WDM 1524 may demultiplex one or more 10GbE optical datasignals, EPON optical data signals, and/or GPON optical data signalsfrom ingress optical data signal 1540. WDM 1524 may transmit the one ormore EPON and/or GPON optical data signals along GPON/EPON 1528 to PONconnector 1502 via port 1522. WDM 1524 may transmit the one or more10GbE optical data signals (e.g., 10GbE UP 1542) out of port 1526 to OPA1544.

The one or more 10GbE optical data signals 10GbE UP 1542 may be receivedby OPA 1544. The one or more optical data signals 10GbE UP 1542 maycomprise 10GbE optical data signals. A gain associated OPA 1544 may bebased at least in part on a distance that 10GbE optical data signalshave to travel, similar to that of BOA 1516. The one or more opticaldata signals 10GbE UP 1542 may be amplified by OPA 1544, and OPA 1544may output multi-wavelength upstream optical data signal 1512 to WDM1513.

WDM 1513 may receive the multi-wavelength upstream optical data signal1512 on port 1510 of WDM 1513, and may output one or more optical datasignals 10GbE UP 1511 to DWDM 1513. The one or more optical data signals10GbE UP 1511 are substantially the same as multi-wavelength upstreamoptical data signal 1512. WDM 1513 may function as a circulator whenreceiving multi-wavelength upstream optical data signal 1512 on port1510 and outputting the one or more optical data signals 10GbE UP 1511on port 1509. The one or more optical data signals 10GbE UP 1511 may bereceived by DWDM 1506.

The one or more optical data signals 10GbE UP 1511 may comprise 10GbEoptical data signals. DWDM 1506 may demultiplex the one or more opticaldata signals 10GbE UP 1511 into individual optical data signals inaccordance with the individual wavelengths of the one or more opticaldata signals 10GbE UP 1511. More specifically, the one or more opticaldata signals 10GbE UP 1511 may be demultiplexed into twenty 10GbEoptical data signals, each of which may have a unique wavelength. DWDM1506 may output each of the twenty 10GbE optical data signals to each ofthe transponders of 20×10GbE UP 1504. Each of the transponders of20×10GbE UP 1504 may convert a received corresponding 10GbE optical datasignal, of the 10GbE optical data signals, into a correspondingelectrical signal. More specifically, a first transceiver in each of thetransponders may convert each of the twenty 10GbE optical data signalsinto the corresponding electrical signal. Each of the transponders mayalso comprise a second transceiver that may convert the correspondingelectrical signal into a SONET/SDH optical data signal with acorresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 1504 may transmitthe twenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

FIG. 16 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure. As shown in FIG. 16, headend1601 is a smart integrated OCML headend, which is a circuit, comprisingone or more EDFAs (e.g., booster optical amplifier (BOA) 1616 andoptical pre-amplifier (OPA) 1633), a DWDM (e.g., DWDM 1605), one or moreWDMs (e.g., WDM 1610 and 1619), one or more DCMs (e.g., DCM 1615 and1635), and an optical switch 1625 to feed a primary optical fiber (e.g.,Primary Fiber 1637) or secondary (backup) optical fiber (e.g., SecondaryFiber 1638). The disclosure provides a method of transporting multiple10GbE and GPON/XGPON/10GEPON signals on the same optical fiber overextended links of up to 60 kms without a cable company having to putoptical amplifiers between the cable's Master Terminal Center (MTC)facility and a field hub or outside plant. The MTC facility may be aninside plant facility where a cable company acquires and combinesservices to be offered to customers. The MTC facility provides thesecombined services to customers, by transmitting and receiving opticalsignals over a plurality of optical fibers to a field hub or outsideplant which connects the plurality of optical fibers to a customer'spremise. The OCML headend may be located in a secondary terminal center(STC) that connects the MTC facility to a field hub or outside planthousing a multiplexer-demultiplexer (MDM) (e.g., MDM 1691).

In one aspect, headend 1601 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 1603) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 1604). 20×10GbE DS 1603 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 1604 mayreceive upstream data over 10GbE wavelengths. Headend 1601 may aconnector (e.g., PON 1602), that may transmit and receive GPON and/orEPON signals on a GPON/EPON connector (e.g., GPON/EPON 1618). Headend1601 may also comprise two wavelength-monitoring ports (e.g.,wavelength-monitoring ports 1636), a primary optical fiber (e.g.,primary optical fiber 1637) and a secondary optical fiber (e.g.,secondary optical fiber 1638) that transmit and receive a plurality ofmulti-wavelength 10GbE and GPON/EPON optical signals. Primary opticalfiber 1637 and secondary optical fiber 1638 may transmit a firstplurality of multi-wavelength 10GbE, GPON, and/or XGPON/10GEPON opticalsignals from headend 1601 to a multiplexer-demultiplexer (MDM) in aoutside plant (e.g., MDM 1691), and may receive a second plurality ofmulti-wavelength 10GbE, GPON, and/or EPON optical signals from MDM 1691.

In one aspect, headend 1601 can transmit and receive up to twentybi-directional 10GbE optical data signals, but the actual number ofoptical data signals may depend on operational needs. That is, headend1601 can transport more or less than twenty 10GbE downstream opticalsignals, or more or less than twenty 10GbE upstream optical datasignals, based on the needs of customers' networks (e.g., Remote PHYNetwork 216, Enterprise Network 218, Millimeter Wave Network 214). Thesecustomer networks may be connected to headend 1601 through an opticalring network (e.g., metro access optical ring network 206).

The operation of headend 1601 may be described by way of the processingof downstream optical data signals transmitted from headend 1601 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. Each of thetransponders of 20×10GbE DS 1603 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 1603 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 1603 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 1605 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 1606) comprising the twenty correspondingsecond optical data signals onto a fiber. More specifically, DWDM 1605may multiplex the twenty corresponding second optical data signals ontothe fiber, wherein the twenty multiplexed corresponding second opticaldata signals compose the multi-wavelength downstream optical datasignal. The multi-wavelength downstream optical data signal may have awavelength comprising the twenty wavelengths of the twenty correspondingsecond optical data signals.

The multi-wavelength downstream optical data signal 10GbE DS 1606, maybe input to a WDM (e.g. WDM 1610). WDM 1610 may be a three port wavedivision multiplexer (WDM), or a three port circulator, that receives10GbE DS 1606 on port 1608 and outputs 10GbE DS 1606 on port 1611 as10GbE DS 1614. 10GbE DS 1614 may be substantially the same as 10GbE DS1606 because WDM 1610 may function as a circulator when 10GbE DS 1606 isinput on port 1608.

10GbE DS 1614 may be input into a DCM (e.g., DCM 1615) to compensate fordispersion that 10GbE DS 1614 may experience after being amplified by anEDFA and multiplexed by a WDM, with other optical data signals, that aredownstream from the DCM. The amplified and multiplexed optical datasignal may be referred to as an egress optical data signal, as it is theoptical data signal that may be transmitted out of headend 1601 over afiber connecting headend 1601 to a field hub or outside plant containingMDM 1691. In some embodiments, DCM 1615 may be configured to balancepositive and/or negative dispersion that may be introduced to the egressoptical data signal by the fiber. In some embodiments, DCM 1615 may beconfigured to compensate for positive (temporal broadening of the egressoptical data signal) and/or negative (temporal contraction of the egressoptical data signal) dispersion introduced by fiber that is 80 km orgreater in length, to reduce the sensitivity or OSNR levels of atransceiver in a DWDM located at a field hub or outside plant. Morespecifically, DCM 1615 may be configured to reduce the sensitivity orOSNR level requirement in a photodetector or fiber-optic sensor in thetransceiver, which may drastically reduce the cost of the transceiversused in the DWDM located at the field hub or outside plant.

DCM 1615 may input 10GbE DS 1614 and may output 10GbE DS 1653 to an EDFA(e.g., BOA 1616). A gain of BOA 1616 may be based at least in part on adistance that a downstream signal has to travel. For example, the gainmay be a function of a fiber attenuation coefficient α, which is ameasure of the intensity of the attenuation of a beam of light as ittraverses a length of an optical fiber segment. The unit of measurementof the fiber attenuation coefficient is decibels (dB) per km (dB/km).For instance, the gain of BOA 1616 may be adjusted based at least inpart on the attenuation coefficient and length of fiber that the egressoptical data signal will travel. More specifically, the gain of BOA 1616may be G=e^((2αL)), where α is the fiber attenuation coefficient, asexplained above, and L is the length of the fiber (e.g., the length ofprimary fiber 1637 and/or the length of secondary fiber 1638). 10GbE DS1653 may be amplified by BOA 1616, and BOA 1616 may output 10GbE DS 1620to port 1617 of WDM 1619.

WDM 1619 may be a WDM that may multiplex 10GbE DS 1620 with one or morePON signals received on (GPON/EPON 1618). 10GbE DS 1620 may be amulti-wavelength optical data signal, wherein the wavelengths comprisethe same wavelengths as 10GbE DS 1606. In some embodiments, thewavelengths of the multi-wavelength optical data signal 10GbE DS 1620may be within the conventional c band of wavelengths, which may includewavelengths within the 1520 nm-1565 nm range. GPON 184 may be a fibercarrying a GPON optical data signal with a wavelength of 1490 nm. TheGPON signal may be input to WDM 1619 on port 1671. WDM 1619 outputs anegress optical data signal from port 1622, which may be amulti-wavelength optical data signal comprising 10GbE, EPON, and GPONoptical data signals. WDM 1619 may multiplex 10GbE DS 1620, EPON opticaldata signals, and GPON optical data signals the same way DWDM 1605multiplexes optical data signals. The egress optical data signal (e.g.,egress optical data signal 1624) may be output on port 1622 of WDM 1619and optical switch 1625 may switch egress optical data signal 1624 outof connector 1626 or connector 1631. In some embodiments, connector 1626may be a primary connector and connector 1631 may be a secondaryconnector or a backup connector. Wavelength monitoring connector 1627may connect connector 1626 to a first port of wavelength-monitoringports 1636, and wavelength monitoring connector 1629 may connectconnector 1631 to a second port of wavelength-monitoring ports 1636.Wavelength-monitoring ports 1636 may monitor the wavelengths in egressoptical data signal 1624 via connector 1626 or connector 1631 dependingon the position of switch 1625. Egress optical data signal 1624 may exitheadend 1601 either via connector 1626 connected to primary fiber 1637or via connector 1631 connected to secondary fiber 1638 depending on theposition of switch 1625. Egress optical data signal 1624 may betransmitted on primary fiber 1637 to a first connector an opticalsplitter (e.g., the optical splitter 1693) inside of or collocated witha MDM (e.g., the MDM 1691). Egress optical data signal 1539 may betransmitted on secondary fiber 1638 to a second connector in opticalsplitter 1693.

Egress optical data signal 1624 may be received at optical splitter 1693as an ingress optical data signal. Optical splitter 1693 may also bereferred to as a beam splitter, and may comprise one or more quartzsubstrates of an integrated waveguide optical power distribution device.Optical splitter 1693 may be a passive optical network device. It may bean optical fiber tandem deice comprising one or more input terminals andone or more output terminals. Optical splitter 1639 may be FusedBiconical Taper (FBT) splitter or Planar Lightwave Circuit (PLC)splitter. Optical splitter 1693 may be a balanced splitter whereinoptical splitter 1693 comprises 2 input fibers and one or more outputfibers over which the ingress optical data signal may be spreadproportionally. In some embodiments, the ingress optical data signal maynot be spread proportionally across the output fibers of opticalsplitter 1693. In some embodiments, optical splitter 1693 may comprise 2input fibers and 2 output fibers. A first input fiber of opticalsplitter 1693 may be connected to primary fiber 1637 and a second inputfiber of optical splitter 1593 may be connected to secondary fiber 1638.

A first output fiber of optical splitter 1693 may be connected to afilter (e.g., C-band block 1692) that filters out packets of light, inthe ingress optical data signal, with wavelengths between 1530 nm and1565 nm. This range of wavelengths may coincide with a C-band ofwavelengths. In some other embodiments, the filter may filter outpackets of light with wavelengths not inclusive of the wavelengthsbetween 1260 nm and 1520 nm and not inclusive of wavelengths between1570 nm and 1660 nm. The packets of light with wavelengths inclusive ofthe wavelengths between 1260 nm and 1520 nm and inclusive of wavelengthsbetween 1570 nm and 1660 nm, may correspond to the wavelengths of thepackets of light carrying the one or more EPON and/or GPON optical datasignals transmitted along GPON/EPON 1618. More specifically, opticalsplitter 1693, may receive one or more downstream EPON and/or GPONoptical data signals 1660, in the ingress optical data signal, thatcorresponds to the one or more EPON and/or GPON optical data signalstransmitted along GPON/EPON 1618. In some embodiments, the one or moredownstream EPON and/or GPON optical data signals 1660 may have the samewavelength as GPON DS 806. Optical splitter 1693 may output the one ormore downstream EPON and/or GPON optical data signals 1660, received inthe ingress optical data signal, to C-band block 1692.

C-band block 1692 may output one or more downstream EPON and/or GPONoptical data signals 1697 corresponding to the one or more downstreamEPON and/or GPON optical data signals 1660 with wavelengths between 1260nm and 1520 nm and wavelengths between 1570 nm and 1660 nm. The C-bandblock 1692 may transmit the one or more downstream EPON and/or GPONoptical data signals 1697 to an express port (not shown in FIG. 16)collocated with, or attached to MDM 1691. In some embodiments, theexpress port may be located within the MDM 1691.

A second output fiber of optical splitter 1693 may be connected tocoupled optical power (COP) 1694. COP 1694 may be a PON device thatmonitors the coupled optical power between Optical Splitter 1693 andDWDM 1696. In some embodiments, the coupled optical power may be apercentage value. For instance, the coupled optical power may be 1%.Optical splitter 1693, may receive one or more downstream 10GbE opticaldata signals, in the ingress optical data signal, that corresponds to10GbE DS 1608. In some embodiments, the one or more downstream 10GbEoptical data signals may have the same wavelength as 10GbE 808. Opticalsplitter 1693 may output the one or more downstream 10GbE optical datasignals 1663, received in the ingress optical data signal, to COP 1694.COP 1694 may output a first percentage of the one or more downstream10GbE optical data signals 1663 to 10GbE upstream and downstream testports (e.g., 10GbE UP & DS Test Ports 1695). The first percentage may bea percentage of the one or more downstream 10GbE optical data signals1663 tested by the 10GbE upstream and downstream test ports. The firstpercentage of the one or more downstream 10GbE optical data signals 1663may be a monitoring signal used by a spectrum analyzer to measureoptical power levels of a specific wavelength. The first percentage ofthe one or more downstream 10GbE optical data signals 1663 may also beused by the spectrum analyzer to analyze certain characteristics of thewavelengths of the first percentage of the one or more downstream 10GbEoptical data signals 1663. COP 1694 may output a second percentage ofthe one or more downstream 10GbE optical data signals 1665 to DWDM 1696.

Because the one or more downstream 10GbE optical data signals 1665 maybe a multi-wavelength downstream optical data signal DWDM 1696 maydemultiplex the one or more downstream 10GbE optical data signals 1665into individual optical data signals in accordance with the individualwavelengths of the one or more downstream 10GbE optical data signals1665. More specifically, the one or more downstream 10GbE optical datasignals 1665 may be demultiplexed into twenty 10GbE optical datasignals, each of which may have a unique wavelength. DWDM 1696 mayoutput each of the twenty 10GbE optical data signals to each of thetransponders of 20×10GbE DS 1698. Each of the transponders of 20×10GbEDS 1698 may be in a RPD (not shown) and may convert a receivedcorresponding 10GbE optical data signal, of the 10GbE optical datasignals, into a corresponding electrical signal. More specifically, afirst transceiver in each of the transponders may convert each of thetwenty 10GbE optical data signals into the corresponding electricalsignal. Each of the transponders may also comprise a second transceiverthat may convert the corresponding electrical signal into a SONET/SDHoptical data signal with a corresponding SONET/SDH optical data signalwavelength. In some embodiments, each of the twenty correspondingSONET/SDH optical data signals may have the same wavelength. In otherembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have unique wavelengths. In some embodiments, the RPD may besimilar in functionality to Remote PHY Node 207. The RPD may convert theSONET/SDH optical data signals into an electrical signal that may betransmitted over one or more coaxial cables. MDM 1691 may be similar infunctionality to MDM 208 and may be connected to the RPD in a waysimilar to the connection between MDM 208 and Remote PHY Node 207.

The operation of MDM 1691 may be further described by way of theprocessing of an upstream optical data signal transmitted to headend1601. Each of the transponders of 20×10GbE UP 1699 may receive aSONET/SDH optical data signal and each of the transponders may convertthe SONET/SDH optical data signal into an electrical signal. Each of thetransponders of 20×10GbE UP 1699 may receive the SONET/SDH optical datasignal from the RPD. The RPD may also convert one or more electricalsignals into the SONET/SDH optical data signal.

More specifically, a first transceiver in the transponder may convertthe SONET/SDH optical data signal into an electrical signal. A secondtransceiver may then convert the electrical signal into a second opticaldata signal, wherein the second optical data signal comprises one ormore packets of light each of which may have a distinct wavelength.Because the one or more packets of light each have a distinctwavelength, the second optical data signal may be said to have thisdistinct wavelength. Thus, the twenty transponders in 20×10GbE UP 1699may each receive a SONET/SDH optical data signal, and each of the twentytransponders may convert the received SONET/SDH optical data signal intoa corresponding second optical data signal, wherein each of thecorresponding second optical data signals has a unique wavelength. Thatis, the wavelength of each of the corresponding second optical datasignals is distinguishable from the wavelength of any of the othercorresponding second optical data signals. Thus 20×10GbE UP 1699 maygenerate twenty corresponding second optical data signals each of whichhas a unique wavelength.

DWDM 1696 may receive twenty corresponding second optical data signalsas an input and output a multi-wavelength upstream optical data signal(e.g., multi-wavelength upstream optical data signal 1664) comprisingthe twenty corresponding second optical data signals. Themulti-wavelength upstream optical data signal 1664 may be a 10GbEoptical data signal. More specifically, DWDM 1696 may multiplex thetwenty corresponding second optical data signals onto the fiberconnecting DWDM 1696 and COP 1694, wherein the twenty multiplexedcorresponding second optical data signals compose the multi-wavelengthdownstream optical data signal. The multi-wavelength optical data signalmay have a wavelength comprising the twenty wavelengths of the twentycorresponding second optical data signals.

The multi-wavelength upstream optical data signal 1664, may be input toCOP 1694. COP 1694 may output a first percentage of the multi-wavelengthupstream optical data signal 1664 to 10GbE upstream and downstream testports (e.g., 10GbE UP & DS Test Ports 1695). The first percentage may bea percentage of the multi-wavelength upstream optical data signal 1664tested by the 10GbE upstream and downstream test ports. The firstpercentage of the multi-wavelength upstream optical data signal 1664 maybe a monitoring signal used by a spectrum analyzer to measure opticalpower levels of a specific wavelength in the multi-wavelength upstreamoptical data signal 1664. The first percentage of the multi-wavelengthupstream optical data signal 1664 may also be used by the spectrumanalyzer to analyze certain characteristics of the wavelengths of thefirst percentage of the multi-wavelength upstream optical data signal1664. COP 1694 may output a second percentage of the multi-wavelengthupstream optical data signal 1664 to optical splitter 1693 as themulti-wavelength upstream optical data signal 1662.

C-band block 1692 may receive one or more upstream EPON and/or GPONoptical data signals 1666 from an express port (not shown in FIG. 16)collocated with, or attached to MDM 1691. In some embodiments, theexpress port may be located within the MDM 1691. C-band block 1692 mayfilter out packets of light, in the one or more upstream EPON and/orGPON optical data signals 1666, with wavelengths between 1530 nm and1565 nm. Thus C-band block 1692 may output one or more upstream EPONand/or GPON optical data signals 1661 with wavelengths between 1260 nmand 1520 nm and wavelengths between 1570 nm and 1660 nm.

Optical splitter 1693 may receive one or more upstream EPON and/or GPONoptical data signals 1661, and may also receive the multi-wavelengthupstream optical data signal 1662, and may multiplex themulti-wavelength one or more upstream EPON and/or GPON optical datasignals 1661 with the multi-wavelength upstream optical data signal1662. Optical splitter 1693 outputs an egress optical data signal, whichmay be a multi-wavelength optical data signal comprising 10GbE,GPON/EPON optical data signals corresponding to the multiplexedmulti-wavelength one or more upstream EPON and/or GPON optical datasignals 1661 and multi-wavelength upstream optical data signal 1662.Optical splitter 1693 may output the egress optical data signal ontoprimary fiber 1637 connecting the optical splitter 1693 to port 1628.Optical splitter 1693 may also output the egress optical data signalonto secondary fiber 1638 connecting the optical splitter 1693 to port1630.

The operation of headend 1601 may be described by way of the processingof upstream optical data signals received at headend 1601 from a fieldhub or outside plant. For instance, a multi-wavelength ingress opticaldata signal, comprising one or more of a 10GbE optical data signal, EPONoptical data signal, and/or GPON optical data signal, may be an upstreamoptical data signal received on primary fiber 1637 or secondary fiber1638 depending on the position of switch 1625. The upstream optical datasignal may be substantially the same as the egress optical data signal.

Because the multi-wavelength ingress optical data signal is routed toport 1622 of WDM 1619, and is altered negligibly between connector 1626and port 1622 or connector 1631 and port 1622, depending on the positionof switch 1625, the multi-wavelength ingress optical data signal may besubstantially the same as ingress optical data signal 1623. Themulti-wavelength ingress optical data signal may traverse 1626 andswitch 1625, before entering WDM 1619 via port 1622 if switch 1625 isconnected to connector 1626. The multi-wavelength ingress optical datasignal may traverse connector 1631 switch 1625, before entering WDM 1619via port 1622 if switch 1625 is connected to connector 1631. WDM 1619may demultiplex one or more 10GbE optical data signals, EPON opticaldata signals, and/or GPON optical data signals from ingress optical datasignal 1623. WDM 1619 may transmit the one or more EPON optical datasignals along GPON 1618 to PON connector 1602. WDM 1619 may transmit theone or more 10GbE optical data signals (e.g., 10GbE UP 1632) out of port1621 to OPA 1633.

A gain of OPA 1633 may be based at least in part on a distance that theSONET/SDH egress optical data signal has to travel. For example, thegain may be a function of a fiber attenuation coefficient α, which is ameasure of the intensity of the attenuation of a beam of light as ittraverses a length of an optical fiber segment on the SONET/SDH opticalnetwork connection. For instance, the gain of OPA 1633 may be adjustedbased at least in part on the attenuation coefficient and length offiber that the egress optical data signal will travel. Morespecifically, the gain of OPA 1633 may be G=e^((2αL)), where α is thefiber attenuation coefficient, as explained above, and L is the lengthof the fiber (e.g., the length of the fiber of the SONET/SDH opticalnetwork connection). 10GbE UP 1632 may be amplified by OPA 1633, and OPA1633 may output 10GbE UP 1634 to DCM 1635.

In some embodiments, DCM 1635 may be configured to balance positiveand/or negative dispersion that may be introduced to a SONET/SDH egressoptical data signal that may exit headend 1601 from 20×10GbE UP 1604.The SONET/SDH egress optical data signal may be an upstream signal froma field hub or outside plant destined for a MTC. For example, a customerpremise may be connected to the field hub or outside plant and may sendone or more packets via a SONET/SDH network to the field hub or outsideplant which may in turn transmit the one or more packets using 10GbEoptical data signals to headend 1601. The one or more packets may bedestined for a company web server connected to the MTC via a backbonenetwork. Because headend 1601 may be collocated in a STC that isconnected to the MTC via an optical ring network, wherein the connectionbetween the STC and MTC is an SONET/SDH optical network connection, DCM1635 may be configured to compensate for positive and/or negativedispersion on the SONET/SDH optical network connection. That is DCM 1635may be configured to reduce temporal broadening of the SONET/SDH ingressoptical data signal or temporal contraction of the SONET/SDH ingressoptical data signal. DCM 1635 may input 10GbE UP 1634 and my output10GbE UP 1613 to WDM 1610.

WDM 1610 may receive 10GbE UP 1613 on port 1612, and may output 10GbE UP1613 on port 1608 as a multi-wavelength upstream optical data signal(e.g., 10GbE UP 1609). 10GbE UP 1609 is substantially the same as 10GbEUP 1613 because WDM 1610 may function as a circulator when 10GbE UP 1613is input to port 1612. 10GbE UP 1609 may be received by DWDM 1605, andDWDM 1605 may demultiplex one or more 10GbE optical data signals from10GbE UP 1609. Because 10GbE UP 1609 is a dispersion compensatedamplified version of the multi-wavelength ingress optical data signal,DWDM 1605 may demultiplex the one or more optical data signals intoindividual optical data signals in accordance with the individualwavelengths of any 10GbE optical data signals in the multi-wavelengthingress optical data signal. More specifically, 10GbE UP 1609 may bedemultiplexed into twenty 10GbE optical data signals, each of which mayhave a unique wavelength. DWDM 1605 may output each of the twenty 10GbEoptical data signals to each of the transponders of 20×10GbE UP 1604.Each of the transponders of 20×10GbE UP 1604 may convert a receivedcorresponding 10GbE optical data signal, of the 10GbE optical datasignals, into a corresponding electrical signal. More specifically, afirst transceiver in each of the transponders may convert each of thetwenty 10GbE optical data signals into the corresponding electricalsignal. Each of the transponders may also comprise a second transceiverthat may convert the corresponding electrical signal into a SONET/SDHoptical data signal with a corresponding SONET/SDH optical data signalwavelength. In some embodiments, each of the twenty correspondingSONET/SDH optical data signals may have the same wavelength. In otherembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have unique wavelengths. The twenty transponders of 20×10GbEUP 1604 may transmit the twenty SONET/SDH optical data signals to theMTC on the SONET/SDH optical network connection.

FIGS. 17A and 17B depicts an access network diagram of an OCML headendcomprising WDMs, a DWDM, optical amplifiers, and dispersion controlmodules (DCMs), in accordance with the disclosure. FIG. 17A shows aschematic of an OCML headend according to at least one embodiment of thedisclosure. As shown in FIG. 17A, headend 1701 is a smart integratedOCML headend, which is a circuit, comprising a DWDM (e.g., DWDM 1705), afirst WDM (e.g., WDM 1713), a second WDM (e.g., WDM 1719), a third WDM(e.g., WDM 1723), a GPON/EPON connector (e.g., GPON/EPON 1724), abooster amplifier BOA (e.g., BOA 1716), an optical pre-amplifier (OPA)(e.g., OPA 1742), a variable optical attenuator (VOA) (e.g., VOA 1721),an optical switch 1726 to feed a primary optical fiber (e.g., PrimaryFiber 1730) or secondary (backup) optical fiber (e.g., Secondary Fiber1731), and a dispersion control module (DCM) (e.g., DCM 1708). DWDM 1705may be similar in functionality to DWDM 106 and WDM 1713, WDM 1719, andWDM 1723 may be similar in functionality to WDM 108. The disclosureprovides a method of transporting multiple 10GbE and GPON/EPON signalson the same optical fiber over extended links of up to 60 kms without acable company having to put optical amplifiers between the cable'sMaster Terminal Center (MTC) facility and a field hub or outside plant.The MTC facility may be an inside plant facility where a cable companyacquires and combines services to be offered to customers. The MTCfacility provides these combined services to customers, by transmittingand receiving optical signals over a plurality of optical fibers to afield hub or outside plant which connects the plurality of opticalfibers to a customer's premise. The OCML headend may be located in asecondary terminal center (STC) that connects the MTC facility to afield hub or outside plant housing a multiplexer-demultiplexer (MDM)(e.g., MDM 208 in FIG. 2).

The EPON signals may operate with the same optical frequencies as GPONand time division multiple access (TDMA). The raw line data rate is 1.25Gbits/s in both the downstream and upstream directions. EPON is fullycompatible with other Ethernet standards, so no conversion orencapsulation is necessary when connecting to Ethernet-based networks oneither end. The same Ethernet frame is used with a payload of up to 1518bytes. EPON may not use a carrier sense multiple access (CSMA)/collisiondetection (CD) access method used in other versions of Ethernet. Thereis a 10-Gbit/s Ethernet version designated as 802.3ay. The line rate maybe 10.3125 Gbits/s. The primary mode is 10 Gbits/s upstream as well asdownstream. A variation uses 10 Gbits/s downstream and 1 Gbit/supstream. The 10-Gbit/s versions use different optical wavelengths onthe fiber, 1575 to 1591 nm downstream and 1260 to 1280 nm upstream sothe 10-Gbit/s system can be wavelength multiplexed on the same fiber asa standard 1-Gbit/s system.

In one aspect, headend 1701 may comprise twenty 10GbE downstream (DS)transponders (e.g., 20×10GbE DS 1703) and twenty 10GbE upstream (UP)transponders (e.g., 20×10GbE UP 1704). 20×10GbE DS 1703 may transmitdownstream data over twenty 10GbE wavelengths. 20×10GbE UP 1704 mayreceive upstream data over 10GbE wavelengths. 20×10GbE DS 1703 maycomprise the same elements and perform the same operations as 20×GbE DS190, and 20×10GbE UP 1704 may comprise the same elements and perform thesame operations as 20×GbE UP 188.

The operation of headend 1701 may be described by way of the processingof downstream optical data signals transmitted from headend 1701 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. Each of thetransponders of 20×10GbE DS 1703 may receive a SONET/SDH optical datasignal from a MTC and each of the transponders may convert the SONET/SDHoptical data signal into an electrical signal. More specifically, afirst transceiver in the transponder may convert the SONET/SDH opticaldata signal into an electrical signal. A second transceiver may thenconvert the electrical signal into a second optical data signal, whereinthe second optical data signal comprises one or more packets of lighteach of which may have a distinct wavelength. Because the one or morepackets of light each have a distinct wavelength, the second opticaldata signal may be said to have this distinct wavelength. Thus, thetwenty transponders in 20×10GbE DS 1703 may each receive a SONET/SDHoptical data signal, and each of the twenty transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals has a unique wavelength. That is, the wavelength of each ofthe corresponding second optical data signals is distinguishable fromthe wavelength of any of the other corresponding second optical datasignals. Thus 20×10GbE DS 1703 may generate twenty corresponding secondoptical data signals each of which has a unique wavelength.

DWDM 1705 may receive the twenty corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 1707) comprising the twenty correspondingsecond optical data signals onto a fiber. The multi-wavelengthdownstream optical data signal 10GbE DS 1707 may be a 10GbE optical datasignal. More specifically, DWDM 1705 may multiplex the twentycorresponding second optical data signals onto the fiber, wherein thetwenty multiplexed corresponding second optical data signals compose themulti-wavelength downstream optical data signal. The multi-wavelengthoptical data signal may have a wavelength comprising the twentywavelengths of the twenty corresponding second optical data signals.

The multi-wavelength downstream optical data signal 10GbE DS 1707, maybe input to DCM 1708. 10GbE DS 1707 may be input into DCM 1708 tocompensate for dispersion that 10GbE DS 1707 may experience after beingamplified by BOA 1716 and multiplexed by WDM 1723, with other opticaldata signals, that are downstream from the DCM. The amplified andmultiplexed optical data signal may be referred to as an egress opticaldata signal, as it is the optical data signal that may be transmittedout of headend 1701 over a fiber connecting headend 1701 to a field hubor outside plant. In some embodiments, DCM 1708 may be configured tobalance positive and/or negative dispersion that may be introduced tothe egress optical data signal by the fiber. In some embodiments, DCM1708 may be configured to compensate for positive (temporal broadeningof the egress optical data signal) and/or negative (temporal contractionof the egress optical data signal) dispersion introduced by fiber thatis 80 km or greater in length, to reduce the sensitivity or OSNR levelsof a transceiver in a DWDM located at a field hub or outside plant. Morespecifically, DCM 1708 may be configured to reduce the sensitivity orOSNR level requirement in a photodetector or fiber-optic sensor in thetransceiver, which may drastically reduce the cost of the transceiversused in the DWDM located at the field hub or outside plant. DCM 1708 mayoutput a dispersion controlled version of 10GbE DS 1707 as 10GbE DS1710.

WDM 1713 may be a three port circulator, that receives multi-wavelengthdownstream optical data signal 10GbE DS 1710 on port 1711, and outputsmulti-wavelength downstream optical data signal 10GbE DS 1710, on port1714 as multi-wavelength downstream optical data signal 10GbE DS 1715 toBOA 1716. In some embodiments, Headend 1701 may not include DCM 1708.

BOA 1716 may have a gain that is based at least in part on a distancethat a downstream signal has to travel. For example, the gain may be afunction of a fiber attenuation coefficient α, which is a measure of theintensity of the attenuation of a beam of light as it traverses a lengthof an optical fiber segment. The unit of measurement of the fiberattenuation coefficient is decibels (dB) per km (dB/km). For instance,BOA 1716 may be adjusted based at least in part on the attenuationcoefficient and length of fiber that the egress optical data signal willtravel. More specifically, the gain BOA 1716 may be G=e^((2αL)), where αis the fiber attenuation coefficient, as explained above, and L is thelength of the fiber (e.g., the length of primary fiber 1730 and/or thelength of secondary fiber 1731). Multi-wavelength downstream opticaldata signal 10GbE DS 1715 may be amplified by BOA 1716, and BOA 1716 mayoutput multi-wavelength downstream optical data signal 10GbE DS 1717 toport 1718 of WDM 1719. WDM 1719 outputs a multi-wavelength downstreamoptical data signal (e.g., multi-wavelength downstream optical datasignal 10GbE DS 1740) from port 1720, which may be substantially thesame as multi-wavelength downstream optical data signal 10GbE DS 1717.Multi-wavelength downstream optical data signal 10GbE DS 1740 may beinput to variable optical amplifier (VOA) 1721.

VOA 1721 may be used to reduce the power levels of Multi-wavelengthdownstream optical data signal 10GbE DS 1740. The power reduction maydone by absorption, reflection, diffusion, scattering, deflection,diffraction, and dispersion, of Multi-wavelength downstream optical datasignal 10GbE DS 1740. VOA 1721 typically have a working wavelength rangein which they absorb all light energy equally. In some embodiments VOA1721 utilize a length of high-loss optical fiber, that operates upon itsinput optical signal power level in such a way that its output signalpower level is less than the input level. For example, multi-wavelengthdownstream optical data signal 10GbE DS 1740 may have an input powerlevel to VOA 1721 that may be greater than the output power level ofmulti-wavelength downstream optical data signal 10GbE DS 1739.

The variability of the output power level of VOA 1721 may be achievedusing a fiber coupler, where some of the power is not sent to the portthat outputs, but to another port. Another possibility is to exploitvariable coupling losses, which are influenced by variable positioningof a fiber end. For example, the transverse position of the output fiberor the width of an air gap between two fibers may be varied, obtaining avariable loss without a strong wavelength dependence. This principle maybe used for single-mode fibers. VOA 17211 may be based on some piece ofdoped fiber, exhibiting absorption within a certain wavelength range.

WDM 1723 may multiplex multi-wavelength downstream optical data signal10GbE DS 1739 and one or more EPON, and/or GPON optical data signals.The EPON and/or GPON optical data signals may be received on a GPON/EPONconnector (e.g., GPON/EPON 1724) from PON port 1702. The resultingmultiplexed optical data signal may be referred to as egress opticaldata signal 1735.

FIG. 17B depicts an access network diagram of amultiplexer-demultiplexer (MDM), in accordance with the disclosure.Egress optical data signal 1735 may be output by WDM 1723 and opticalswitch 1726 may switch egress optical data signal 1735 onto connector1727 or connector 1734 depending on the position of switch 1726. In someembodiments, connector 1727 may be a primary connector and connector1734 may be a secondary connector or a backup connector. Wavelengthmonitoring connector 1728 may connect connector 1727 to a first port ofwavelength-monitoring ports 1744, and wavelength monitoring connector1733 may connect connector 1734 to a second port ofwavelength-monitoring ports 1744. Wavelength-monitoring ports 1744 maymonitor the wavelengths in egress optical data signal 1735 via connector1727 or connector 1734 depending on the position of switch 1726. Egressoptical data signal 1735 may exit headend 1701 via connector 1727connected to primary fiber 1730, and may be received on a firstconnector in the field hub or outside plant. Egress optical data signal1735 may exit headend 1701 via connector 1734 connected to secondaryfiber 1731, and may be received on a second connector in the field hubor outside plant. The field hub or outside plant may include a MDM withthe first connector and the second connector.

Egress optical data signal 1735 may be received at optical splitter 1793as an ingress optical data signal. Optical splitter 1793 may also bereferred to as a beam splitter, and may comprise one or more quartzsubstrates of an integrated waveguide optical power distribution device.Optical splitter 1793 may be a passive optical network device. It may bean optical fiber tandem deice comprising one or more input terminals andone or more output terminals. Optical splitter 1739 may be FusedBiconical Taper (FBT) splitter or Planar Lightwave Circuit (PLC)splitter. Optical splitter 1793 may be a balanced splitter whereinoptical splitter 1793 comprises 2 input fibers and one or more outputfibers over which the ingress optical data signal may be spreadproportionally. In some embodiments, the ingress optical data signal maynot be spread proportionally across the output fibers of opticalsplitter 1793. In some embodiments, optical splitter 1793 may comprise 2input fibers and 2 output fibers. A first input fiber of opticalsplitter 1793 may be connected to primary fiber 1737 and a second inputfiber of optical splitter 1793 may be connected to secondary fiber 1738.

A first output fiber of optical splitter 1793 may be connected to afilter (e.g., C-band block 1792) that filters out packets of light, inthe ingress optical data signal, with wavelengths between 1530 nm and1565 nm. This range of wavelengths may coincide with a C-band ofwavelengths. In some other embodiments, the filter may filter outpackets of light with wavelengths not inclusive of the wavelengthsbetween 1260 nm and 1520 nm and not inclusive of wavelengths between1570 nm and 1660 nm. The packets of light with wavelengths inclusive ofthe wavelengths between 1260 nm and 1520 nm and inclusive of wavelengthsbetween 1570 nm and 1660 nm, may correspond to the wavelengths of thepackets of light carrying the one or more EPON and/or GPON optical datasignals transmitted along GPON/EPON 1724. More specifically, opticalsplitter 1793, may receive one or more downstream EPON and/or GPONoptical data signals 1760, in the ingress optical data signal, thatcorresponds to the one or more EPON and/or GPON optical data signalstransmitted along GPON/EPON 1724. In some embodiments, the one or moredownstream EPON and/or GPON optical data signals 1760 may have the samewavelength as GPON DS 806. Optical splitter 1793 may output the one ormore downstream EPON and/or GPON optical data signals 1760, received inthe ingress optical data signal, to C-band block 1792.

C-band block 1792 may output one or more downstream EPON and/or GPONoptical data signals 1797 corresponding to the one or more downstreamEPON and/or GPON optical data signals 1760 with wavelengths between 1260nm and 1520 nm and wavelengths between 1570 nm and 1660 nm. The C-bandblock 1792 may transmit the one or more downstream EPON and/or GPONoptical data signals 1797 to an express port (not shown in FIG. 17)collocated with, or attached to MDM 1791. In some embodiments, theexpress port may be located within the MDM 1791.

A second output fiber of optical splitter 1793 may be connected to COP1794. COP 1794 may be a PON device that monitors the coupled opticalpower between Optical Splitter 1793 and DWDM 1796. In some embodiments,the coupled optical power may be a percentage value. For instance, thecoupled optical power may be 1%. Optical splitter 1793, may receive oneor more downstream 10GbE optical data signals, in the ingress opticaldata signal, that corresponds to 10GbE DS 1708. In some embodiments, theone or more downstream 10GbE optical data signals may have the samewavelength as 10GbE 808. Optical splitter 1793 may output the one ormore downstream 10GbE optical data signals 1763, received in the ingressoptical data signal, to COP 1794. COP 1794 may output a first percentageof the one or more downstream 10GbE optical data signals 1763 to 10GbEupstream and downstream test ports (e.g., 10GbE UP & DS Test Ports1795). The first percentage may be a percentage of the one or moredownstream 10GbE optical data signals 1763 tested by the 10GbE upstreamand downstream test ports. The first percentage of the one or moredownstream 10GbE optical data signals 1763 may be a monitoring signalused by a spectrum analyzer to measure optical power levels of aspecific wavelength. The first percentage of the one or more downstream10GbE optical data signals 1763 may also be used by the spectrumanalyzer to analyze certain characteristics of the wavelengths of thefirst percentage of the one or more downstream 10GbE optical datasignals 1763. COP 1794 may output a second percentage of the one or moredownstream 10GbE optical data signals 1765 to DWDM 1796.

Because the one or more downstream 10GbE optical data signals 1765 maybe a multi-wavelength downstream optical data signal DWDM 1796 maydemultiplex the one or more downstream 10GbE optical data signals 1765into individual optical data signals in accordance with the individualwavelengths of the one or more downstream 10GbE optical data signals1765. More specifically, the one or more downstream 10GbE optical datasignals 1765 may be demultiplexed into twenty 10GbE optical datasignals, each of which may have a unique wavelength. DWDM 1796 mayoutput each of the twenty 10GbE optical data signals to each of thetransponders of 20×10GbE DS 1798. Each of the transponders of 20×10GbEDS 1798 may be in a RPD (not shown) and may convert a receivedcorresponding 10GbE optical data signal, of the 10GbE optical datasignals, into a corresponding electrical signal. More specifically, afirst transceiver in each of the transponders may convert each of thetwenty 10GbE optical data signals into the corresponding electricalsignal. Each of the transponders may also comprise a second transceiverthat may convert the corresponding electrical signal into a SONET/SDHoptical data signal with a corresponding SONET/SDH optical data signalwavelength. In some embodiments, each of the twenty correspondingSONET/SDH optical data signals may have the same wavelength. In otherembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have unique wavelengths. In some embodiments, the RPD may besimilar in functionality to Remote PHY Node 207. The RPD may convert theSONET/SDH optical data signals into an electrical signal that may betransmitted over one or more coaxial cables. MDM 1791 may be similar infunctionality to MDM 208 and may be connected to the RPD in a waysimilar to the connection between MDM 208 and Remote PHY Node 207.

The operation of MDM 1791 may be further described by way of theprocessing of an upstream optical data signal transmitted to headend1701. Each of the transponders of 20×10GbE UP 1799 may receive aSONET/SDH optical data signal and each of the transponders may convertthe SONET/SDH optical data signal into an electrical signal. Each of thetransponders of 20×10GbE UP 1799 may receive the SONET/SDH optical datasignal from the RPD. The RPD may also convert one or more electricalsignals into the SONET/SDH optical data signal.

More specifically, a first transceiver in the transponder may convertthe SONET/SDH optical data signal into an electrical signal. A secondtransceiver may then convert the electrical signal into a second opticaldata signal, wherein the second optical data signal comprises one ormore packets of light each of which may have a distinct wavelength.Because the one or more packets of light each have a distinctwavelength, the second optical data signal may be said to have thisdistinct wavelength. Thus, the twenty transponders in 20×10GbE UP 1799may each receive a SONET/SDH optical data signal, and each of the twentytransponders may convert the received SONET/SDH optical data signal intoa corresponding second optical data signal, wherein each of thecorresponding second optical data signals has a unique wavelength. Thatis, the wavelength of each of the corresponding second optical datasignals is distinguishable from the wavelength of any of the othercorresponding second optical data signals. Thus 20×10GbE UP 1799 maygenerate twenty corresponding second optical data signals each of whichhas a unique wavelength.

DWDM 1796 may receive twenty corresponding second optical data signalsas an input and output a multi-wavelength upstream optical data signal(e.g., multi-wavelength upstream optical data signal 1764) comprisingthe twenty corresponding second optical data signals. Themulti-wavelength upstream optical data signal 1764 may be a 10GbEoptical data signal. More specifically, DWDM 1796 may multiplex thetwenty corresponding second optical data signals onto the fiberconnecting DWDM 1796 and COP 1794, wherein the twenty multiplexedcorresponding second optical data signals compose the multi-wavelengthdownstream optical data signal. The multi-wavelength optical data signalmay have a wavelength comprising the twenty wavelengths of the twentycorresponding second optical data signals.

The multi-wavelength upstream optical data signal 1764, may be input toCOP 1794. COP 1794 may output a first percentage of the multi-wavelengthupstream optical data signal 1664 to 10GbE upstream and downstream testports (e.g., 10GbE UP & DS Test Ports 1795). The first percentage may bea percentage of the multi-wavelength upstream optical data signal 1764tested by the 10GbE upstream and downstream test ports. The firstpercentage of the multi-wavelength upstream optical data signal 1764 maybe a monitoring signal used by a spectrum analyzer to measure opticalpower levels of a specific wavelength in the multi-wavelength upstreamoptical data signal 1764. The first percentage of the multi-wavelengthupstream optical data signal 1764 may also be used by the spectrumanalyzer to analyze certain characteristics of the wavelengths of thefirst percentage of the multi-wavelength upstream optical data signal1764. COP 1794 may output a second percentage of the multi-wavelengthupstream optical data signal 1764 to optical splitter 1793 as themulti-wavelength upstream optical data signal 1762.

C-band block 1792 may receive one or more upstream EPON and/or GPONoptical data signals 1766 from an express port (not shown in FIG. 17)collocated with, or attached to MDM 1791. In some embodiments, theexpress port may be located within the MDM 1791. C-band block 1792 mayfilter out packets of light, in the one or more upstream EPON and/orGPON optical data signals 1766, with wavelengths between 1530 nm and1565 nm. Thus C-band block 1792 may output one or more upstream EPONand/or GPON optical data signals 1761 with wavelengths between 1260 nmand 1520 nm and wavelengths between 1570 nm and 1660 nm.

Optical splitter 1793 may receive one or more upstream EPON and/or GPONoptical data signals 1761, and may also receive the multi-wavelengthupstream optical data signal 1762, and may multiplex themulti-wavelength one or more upstream EPON and/or GPON optical datasignals 1761 with the multi-wavelength upstream optical data signal1762. Optical splitter 1793 outputs an egress optical data signal, whichmay be a multi-wavelength optical data signal comprising 10GbE,GPON/EPON optical data signals corresponding to the multiplexedmulti-wavelength one or more upstream EPON and/or GPON optical datasignals 1761 and multi-wavelength upstream optical data signal 1762.Optical splitter 1793 may output the egress optical data signal ontoprimary fiber 1730 connecting the optical splitter 1793 to port 1729.Optical splitter 1793 may also output the egress optical data signalonto secondary fiber 1731 connecting the optical splitter 1793 to port1731.

The operation of headend 1701 may be described by way of the processingof upstream optical data signals received at headend 1701 from a fieldhub or outside plant. For instance, a multi-wavelength ingress opticaldata signal, comprising one or more of a 10GbE optical data signal, EPONoptical data signal, and/or GPON optical data signal or a 10GEPN.XGPONmay be an upstream optical data signal received on primary fiber 1730 orsecondary fiber 1731 depending on the position of switch 1726. Theupstream optical data signal may be substantially the same as the egressoptical data signal.

Multi-wavelength ingress optical data signal 1736 may traverse connector1727 and switch 1726, before entering WDM 1723 via port 1737 if switch1726 is connected to connector 1727. Multi-wavelength ingress opticaldata signal 1736 may traverse connector 1734 and switch 1726, beforeentering WDM 1723 via port 1737 if switch 1726 is connected to connector1727. WDM 1723 may demultiplex one or more 10GbE optical data signals,EPON optical data signals, and/or GPON optical data signals frommulti-wavelength ingress optical data signal 1736. WDM 1723 may transmitthe one or more EPON and/or GPON optical data signals along GPON/EPON1724 to PON connector 1702 via port 1725. WDM 1723 may transmit the oneor more 10GbE optical data signals (e.g., 10GbE UP 1741) out of port1738 to OPA 1742.

The one or more 10GbE optical data signals 10GbE UP 1741 may be receivedby OPA 1742. The one or more optical data signals 10GbE UP 1741 maycomprise 10GbE optical data signals. A gain associated OPA 1742 may bebased at least in part on a distance that 10GbE optical data signalshave to travel, similar to that of BOA 1716. The one or more opticaldata signals 10GbE UP 1741 may be amplified by OPA 1742, and OPA 1742may output multi-wavelength upstream optical data signal 1743 to WDM1713.

WDM 1713 may receive the multi-wavelength upstream optical data signal1743 on port 1712, and may output one or more optical data signals 10GbEUP 1709 to DCM 1708. DCM 1708 may perform one or more operations on oneor more optical data signals 10GbE UP 1709 to compensate for anydispersion that may have been introduced by circuit components (e.g.,WDM 1713, OPA 1742, or WDM 1723) or imperfections or issues with anoptical fiber (e.g., primary fiber 1730 or secondary fiber 1731). DCM1708 may output one or more optical data signals 10GbE UP 1706 to DWDM1705. The one or more optical data signals 10GbE UP 1709 aresubstantially the same as multi-wavelength upstream optical data signal1743. WDM 1713 may function as a circulator when receivingmulti-wavelength upstream optical data signal 1743 on port 1712. The oneor more optical data signals 10GbE UP 1706 may be received by DWDM 1705.

The one or more optical data signals 10GbE UP 1706 may comprise 10GbEoptical data signals. DWDM 1705 may demultiplex the one or more opticaldata signals 10GbE UP 1706 into individual optical data signals inaccordance with the individual wavelengths of the one or more opticaldata signals 10GbE UP 1706. More specifically, the one or more opticaldata signals 10GbE UP 1706 may be demultiplexed into twenty 10GbEoptical data signals, each of which may have a unique wavelength. DWDM1705 may output each of the twenty 10GbE optical data signals to each ofthe transponders of 20×10GbE UP 1704. Each of the transponders of20×10GbE UP 1704 may convert a received corresponding 10GbE optical datasignal, of the 10GbE optical data signals, into a correspondingelectrical signal. More specifically, a first transceiver in each of thetransponders may convert each of the twenty 10GbE optical data signalsinto the corresponding electrical signal. Each of the transponders mayalso comprise a second transceiver that may convert the correspondingelectrical signal into a SONET/SDH optical data signal with acorresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 1704 may transmitthe twenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

The operation of headend 1701 may be described by way of the processingof upstream optical data signals received at headend 1701 from a fieldhub or outside plant. For instance, a multi-wavelength ingress opticaldata signal, comprising one or more of a 10GbE optical data signal, EPONoptical data signal, and/or GPON optical data signal or a 10GEPN.XGPONmay be an upstream optical data signal received on primary fiber 1730 orsecondary fiber 1731 depending on the position of switch 1726.

Multi-wavelength ingress optical data signal 1736 may traverse connector1727 and switch 1726, before entering WDM 1723 via port 1737 if switch1726 is connected to connector 1727. Multi-wavelength ingress opticaldata signal 1736 may traverse connector 1734 and switch 1726, beforeentering WDM 1723 via port 1737 if switch 1726 is connected to connector1727. WDM 1723 may demultiplex one or more 10GbE optical data signals,EPON optical data signals, and/or GPON optical data signals frommulti-wavelength ingress optical data signal 1736. WDM 1723 may transmitthe one or more EPON and/or GPON optical data signals along GPON/EPON1724 to PON connector 1702 via port 1725. WDM 1723 may transmit the oneor more 10GbE optical data signals (e.g., 10GbE UP 1741) out of port1738 to OPA 1742.

The one or more 10GbE optical data signals 10GbE UP 1741 may be receivedby OPA 1742. The one or more optical data signals 10GbE UP 1741 maycomprise 10GbE optical data signals. A gain associated OPA 1742 may bebased at least in part on a distance that 10GbE optical data signalshave to travel, similar to that of BOA 1716. The one or more opticaldata signals 10GbE UP 1741 may be amplified by OPA 1742, and OPA 1742may output multi-wavelength upstream optical data signal 1743 to WDM1713.

WDM 1713 may receive the multi-wavelength upstream optical data signal1743 on port 1712, and may output one or more optical data signals 10GbEUP 1709 to DCM 1708. DCM 1708 may perform one or more operations on oneor more optical data signals 10GbE UP 1709 to compensate for anydispersion that may have been introduced by circuit components (e.g.,WDM 1713, OPA 1742, or WDM 1723) or imperfections or issues with anoptical fiber (e.g., primary fiber 1730 or secondary fiber 1731). DCM1708 may output one or more optical data signals 10GbE UP 1706 to DWDM1705. The one or more optical data signals 10GbE UP 1709 aresubstantially the same as multi-wavelength upstream optical data signal1743. WDM 1713 may function as a circulator when receivingmulti-wavelength upstream optical data signal 1743 on port 1712. The oneor more optical data signals 10GbE UP 1706 may be received by DWDM 1705.

The one or more optical data signals 10GbE UP 1706 may comprise 10GbEoptical data signals. DWDM 1705 may demultiplex the one or more opticaldata signals 10GbE UP 1706 into individual optical data signals inaccordance with the individual wavelengths of the one or more opticaldata signals 10GbE UP 1706. More specifically, the one or more opticaldata signals 10GbE UP 1706 may be demultiplexed into twenty 10GbEoptical data signals, each of which may have a unique wavelength. DWDM1705 may output each of the twenty 10GbE optical data signals to each ofthe transponders of 20×10GbE UP 1704. Each of the transponders of20×10GbE UP 1704 may convert a received corresponding 10GbE optical datasignal, of the 10GbE optical data signals, into a correspondingelectrical signal. More specifically, a first transceiver in each of thetransponders may convert each of the twenty 10GbE optical data signalsinto the corresponding electrical signal. Each of the transponders mayalso comprise a second transceiver that may convert the correspondingelectrical signal into a SONET/SDH optical data signal with acorresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty corresponding SONET/SDH optical datasignals may have the same wavelength. In other embodiments, each of thetwenty corresponding SONET/SDH optical data signals may have uniquewavelengths. The twenty transponders of 20×10GbE UP 1704 may transmitthe twenty SONET/SDH optical data signals to the MTC on the SONET/SDHoptical network connection.

FIG. 18 depicts an access network diagram of an OCML headend and outsideplant, in accordance with the disclosure. At block 1802 the OCML headendmay receive one or more first optical data signals from a network. Atblock 1804 the OCML headend may combine the one or more first opticaldata signals. At block 1806 the OCML headend may generate a secondoptical data signal based at least in part on applying the combined oneor more first optical data signals to a dispersion compensation module(DCM). At block 1808 the OCML headend may generate a third optical datasignal based at least in part on applying the second optical data signalto an optical amplifier. At block 1810 the OCML headend may combine thethird optical data signal with one or more passive optical network (PON)signals into a fourth optical data signal. At block 1812 the OCMLheadend may transmit the fourth optical data signal to a field hub.

FIG. 18 may cover the operation of the OCML headend in FIGS. 1, 10, 11,14, 16, and 17 in the downstream.

FIG. 19 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure. At block 1902 the OCMLheadend may receive one or more first optical data signals from anetwork. At block 1904 the OCML headend may generate a second opticaldata signal by combining the one or more first optical data signals. Atblock 1906 the OCML headend may generate a third optical data signal bycombining the second optical data signal with one or more passiveoptical network (PON) signals. At block 1908 the headend may transmitthe fourth optical data signal to a field hub. The flowchart in FIG. 19may cover the operation of the terminal in FIGS. 3, 5, 6, 12, and 15 inthe downstream.

FIG. 20 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure. At block 2002 the OCMLheadend may receive one or more first optical data signals from anetwork. At block 2004 the OCML headend may combine the one or morefirst optical data signals. At block 2006 the OCML headend may generatea second optical data signal based at least in part on applying thecombined one or more first optical data signals to a dispersioncompensation module (DCM). At block 2008 the OCML headend may generate athird optical data signal based at least in part on applying the secondoptical data signal to an optical amplifier. At block 2010 the OCMLheadend may generate a fourth optical data signal based at least in parton applying the third optical data signal to an variable opticalattenuator. At block 2012 the OCML headend may combine the fourthoptical data signal with one or more passive optical network (PON)signals into a fifth optical data signal. At block 2014 the OCMLterminal may transmit the fifth optical data signal to a field hub. Theflowchart in FIG. 20 may cover the operation of FIG. 13 in thedownstream.

FIG. 21 depicts a schematic of an OCML headend according to at least oneembodiment of the disclosure. The schematic depicted in FIG. 21 may bean alternative embodiment to the OCML headend of FIG. 1, or any otherOCML systems described herein. As shown in FIG. 21, headend 2101 may bea smart integrated OCML headend, which may be a circuit comprising oneor more amplifiers (e.g., Optical amplifiers 2102 and 2104), one or moreDWDMs (e.g., DWDM 2106), one or more circulators (e.g., circulator 2108and 2109), one or more DCMs (e.g., DCM 2112 and 2114) (which may betunable DCMs), one or more VOAs (e.g., VOA 2115), one or more WDMs(e.g., WDM 2210, WDM 2211, and WDM 2212), and one or more opticalswitches (e.g., optical switch 2116) to feed a primary optical fiber(e.g., Primary Fiber 2176) or secondary (backup) optical fiber (e.g.,Secondary Fiber 2174) (as well as any number of additional fibers). Thedisclosure may provide a method for transporting multiple 10GbE,GPON/XGPON/10GEPON, 25G Non-return-to-zero (NRZ), 25G Quasi-Coherent, 25and/or 50G Pulse-Amplitude Modulation (PAM4), 100-600G Coherent, and/orDuo-Binary signals (and/or any other type of signal on the same opticalfiber over extended links of up to at least 60 kilometers or morewithout placing optical amplifiers between the cable's MTC facility(which, as mentioned above, may simply be any type of central hublocation in a cable network) and a field hub or outside plant. The MTCfacility may be an inside plant facility where a cable company acquiresand combines services to be offered to customers. The MTC facility mayprovide these combined services to customers, by transmitting andreceiving optical signals over a plurality of optical fibers to a fieldhub or outside plant which connects the plurality of optical fibers to acustomer's premise. The OCML headend may be located in a secondaryterminal center (STC) that connects the MTC facility to a field hub oroutside plant housing a multiplexer-demultiplexer (MDM) (e.g., MDM 208in FIG. 2). The OCML headend may also be located in the MTC or in anyother location along a transmission path of the signals.

In one aspect, headend 2101 may comprise at least twenty four 10GbEdownstream (DS) transponders (e.g., 24×10GbE DS 2190) and at leasttwenty four 10GbE upstream (UP) transponders (e.g., 24×10GbE UP 2188).24×10GbE DS 2190 may transmit downstream data over twenty four 10GbEwavelengths. 24×10GbE UP 2188 may receive upstream data over 10GbEwavelengths. Although the DS and UP transponders (e.g., 24×10GbE DS 2190and/or 24×10GbE UP 2188) are described as transmitting 10GbE signals,any other signal may be transmitted as well (e.g., GPON/XGPON/10GEPON,25G Non-return-to-zero (NRZ), 25G Quasi-Coherent, 25 and/or 50GPulse-Amplitude Modulation (PAM4), 100-600G Coherent, Duo-Binary, and/orany other type of signal). The use of 24 downstream and 24 upstreamwavelengths may allow a full C band capability of 48 channels.Additionally, the downstream and upstream signal wavelengths may becapable transported on adjacent channels, rather than using a block ofchannels for downstream transmission and a block of channels forupstream transmission, with a guard band of a particular number ofwavelengths included between the two channel blocks. Alternatively, thedownstream and upstream signal wavelengths may still be transmitted inseparate blocks, however. An example of downstream and upstream channelsand their corresponding wavelengths may be provided below in Table 1.

TABLE 1 Downstream Upstream Pair ITU Wavelength ITU Wavelength 1 141566.31 38 1546.92 2 15 1565.5 39 1546.12 3 16 1564.68 40 1545.32 4 171563.86 41 1544.53 5 18 1563.05 42 1543.73 6 19 1562.23 43 1542.94 7 201561.42 44 1542.14 8 21 1560.61 45 1541.35 9 22 1559.79 46 1540.56 10 231558.98 47 1539.77 11 24 1558.17 48 1538.98 12 25 1557.36 49 1538.19 1326 1556.56 50 1537.4 14 27 1555.75 51 1536.61 15 28 1554.94 52 1535.8216 29 1554.13 53 1535.04 17 30 1553.33 54 1534.25 18 31 1552.52 551533.47 19 32 1551.72 56 1532.68 20 33 1550.92 57 1531.9 21 34 1550.1258 1531.12 22 35 1549.32 59 1530.33 23 36 1548.52 60 1529.55 24 371547.72 61 1528.77

Headend 2101 may also comprise two PON 2124 connectors, one of which maybe a GPON connector (e.g., GPON 2184) and one of which may be anXGPON/10GEPON connector (e.g., XGPON/10GEPON 2182). Headend 2101 mayalso comprise two wavelength-monitoring ports (e.g.,wavelength-monitoring ports 126), a primary optical fiber (e.g., primaryoptical fiber 2176) and a secondary optical fiber (e.g., secondaryoptical fiber 2174) that transmit and receive a plurality ofmulti-wavelength 10GbE and GPON/XGPON/10GEPON optical signals. Primaryoptical fiber 2176 and secondary optical fiber 2174 may transmit a firstplurality of multi-wavelength 10GbE, GPON, and/or XGPON/10GEPON opticalsignals from headend 2101 to an outside plant (not illustrated in FIG.21), and may receive a second plurality of multi-wavelength 10GbE, GPON,and/or XGPON/10GEPON optical signals from the outside plant. In someembodiments, any other number of optical fibers may be provided (e.g.,more than just the primary and secondary optical fibers).

In some embodiments, 24×10GbE DS 2190 and 24×10GbE UP 2188 may compriseconnectors belonging to the laser shock hardening (LSH) family ofconnectors designed to transmit and receive optical data signals betweenDWDM 2106, and one or more servers (not shown). In other embodiments,24×10GbE DS 2190 and 24×10GbE UP 2188 may also comprise E2000connectors, and may utilize a 1.25 millimeter (mm) ferrule. 24×10GbE DS2190 and 24×10GbE UP 2188 may be installed with a snap-in and push-pulllatching mechanism, and may include a spring-loaded shutter whichprotects the ferrule from dust and scratches. The shutter may closeautomatically once the connector is disengaged, locking out impurities,which could later result in network failure, and locking in possiblydamaging lasers. 24×10GbE DS 2190 and 24×10GbE UP 2188 may operate in asingle mode or a multimode.

In single mode, 204×10GbE DS 2190 and 24×10GbE UP 2188 only one mode oflight may be allowed to propagate. Because of this, the number of lightreflections created as the light passes through the core of single mode24×10GbE DS 2190 and 24×10GbE UP 2188 decreases, thereby loweringattenuation and creating the ability for the optical data signal totravel further. Single mode may be for use in long distance, higherbandwidth connections between one or more servers and DWDM 2106.

In multimode, 24×10GbE DS 2190 and 24×10GbE UP 2188, may have a largediameter core that allows multiple modes of light to propagate. Becauseof this, the number of light reflections created as the light passesthrough the core increase, creating the ability for more data to passthrough at a given time. Multimode 24×10GbE DS 2190 and 24×10GbE UP2188, may generate high dispersion and a attenuation rate, which mayreduce the quality of an optical data signal transmitted over longerdistances. Therefore multimode may be used to transmit optical datasignals over shorter distances.

In one aspect, headend 2101 can transmit and receive up to at leasttwenty four bi-directional 10GbE optical data signals, but the actualnumber of optical data signals may depend on operational needs. That is,headend 2101 can transport more or less than twenty four 10GbEdownstream optical signals, or more or less than twenty four 10GbEupstream optical data signals, based on the needs of customers' networks(e.g., Remote PHY Network 216, Enterprise Network 218, Millimeter WaveNetwork 214). These customer networks may be connected to headend 2101through an optical ring network (e.g., metro access optical ring network206).

The operation of headend 2101 may be described by way of the processingof downstream optical data signals transmitted from headend 2101 to afield hub or outside plant, and the processing of upstream optical datasignals received from the field hub or outside plant. In terms ofdownstream processing, each of the transponders of 24×10GbE DS 2190 mayreceive a SONET/SDH optical data signal from a MTC and each of thetransponders may convert the SONET/SDH optical data signal into anelectrical signal. More specifically, a first transceiver in thetransponder may convert the SONET/SDH optical data signal into anelectrical signal. A second transceiver may then convert the electricalsignal into a second optical data signal, wherein the second opticaldata signal comprises one or more packets of light each of which mayhave a distinct wavelength. Because the one or more packets of lighteach have a distinct wavelength, the second optical data signal may besaid to have this distinct wavelength. Thus, the twenty fourtransponders in 24×10GbE DS 2190 may each receive a SONET/SDH opticaldata signal, and each of the twenty four transponders may convert thereceived SONET/SDH optical data signal into a corresponding secondoptical data signal, wherein each of the corresponding second opticaldata signals may have a unique wavelength. That is, the wavelength ofeach of the corresponding second optical data signals may bedistinguishable from the wavelength of any of the other correspondingsecond optical data signals. Thus 24×10GbE DS 2190 may generate twentyfour corresponding second optical data signals each of which has aunique wavelength.

DWDM 2106 may receive the twenty four corresponding second optical datasignals as an input and output a multi-wavelength downstream opticaldata signal (e.g., 10GbE DS 2198) comprising the twenty fourcorresponding second optical data signals onto a fiber. Morespecifically, DWDM 2106 may multiplex the twenty four correspondingsecond optical data signals onto the fiber, wherein the twenty fourmultiplexed corresponding second optical data signals compose themulti-wavelength downstream optical data signal. The multi-wavelengthdownstream optical data signal may have a wavelength comprising thetwenty four wavelengths of the twenty four corresponding second opticaldata signals.

The multi-wavelength downstream optical data signal 10GbE DS 2198, maybe input to a circulator (e.g. circulator 2108). The circulator 2108 mayallow additional optical wavelengths to be utilized (e.g., the fullarray of wavelengths included in the 48 total channels) and may enabletechnologies such as Quasi-Coherent and PAM4 (where the DS and UPwavelengths may be closer together) to be transported in an OCML-MDMinfrastructure. The circulator 2108 may enable the use of the samewavelength for both downstream and upstream and upstream purposes.Circulators may be one directional, non-reciprocating (any changes inthe properties of the light caused by passing through the device may notbe reversed by traveling in the opposite direction) devices. Circulatorscan be used to separate optical signals that travel in oppositedirections in one single fiber. Fiber Circulators have high isolationand low insertion loss. Circulator 2108 may be round baud single or dualstage circulator that receives 10GbE DS 2198 on port 2194 and outputs10GbE DS 2198 on port 2186 as 10GbE DS 2172. 10GbE DS 2172 may besubstantially the same as 10GbE DS 2198.

After being output by the circulator 2108, 10GbE DS 2172 may be inputinto a DCM (e.g., DCM 2112) to compensate for dispersion that 10GbE DS2172 may experience after being amplified by an EDFA and multiplexed bya circulator, with other optical data signals, that are downstream fromthe DCM. The amplified and multiplexed optical data signal may bereferred to as an egress optical data signal, as it is the optical datasignal that may be transmitted out of headend 2101 over a fiberconnecting headend 2101 to a field hub or outside plant. In someembodiments, DCM 2112 may be configured to balance positive and/ornegative dispersion that may be introduced to the egress optical datasignal by the fiber. In some embodiments, DCM 2112 may be configured tocompensate for positive (temporal broadening of the egress optical datasignal) and/or negative (temporal contraction of the egress optical datasignal) dispersion introduced by fiber that is 60 km or greater inlength, to reduce the sensitivity or OSNR levels of a transceiver in aDWDM located at a field hub or outside plant. More specifically, DCM2112 may be configured to reduce the sensitivity or OSNR levelrequirement in a photodetector or fiber-optic sensor in the transceiver,which may drastically reduce the cost of the transceivers used in theDWDM located at the field hub or outside plant. Additionally, the DCM2112 may also be tunable. That is, the DCMs can be tuned based on thetransmission distance of a signal. For example, if a signal is beingtransmitted over a 60 km fiber, the tunable DCM may be tuned differentlythan if the signal were being transmitted over a 5 km fiber. The tunableDCM may be a Fiber Bragg Grating (FBG) type DCM previously described.Submitting the tunable DCM (e.g., the FBG) to a temperature gradient mayallow a grating chirp to be changed and, accordingly, the dispersionlevel of the tunable DCM to be tuned. Seven single gratings can be usedfor producing negative dispersion over a typical range from −800 to−2000 ps/nm or for producing a similar positive dispersion range. Thismeans that the fiber link can be totally managed for dispersion for alldistances which may range from 5 km to 60 km, or even greater distances.

DCM 2112 may input 10GbE DS 2172 and may output 10GbE DS 2170 to anamplifier (e.g., booster optical amplifier 2102), which may be an EDFA.The booster optical amplifier 2102, as well as any other amplifiersdescribed herein, may allow operation over a full transmission spectrum,which may include at least 48 transmission channels. That is, thebooster optical amplifier 2102 may be a wide-band amplifier. To support48 channels, the EDFA may optimize gain flatness and noise for thebroader channel range (e.g., 40 channels included with some of the otherOCML systems described herein to 48 channels in OCML headend 2101). Again of the booster optical amplifier (e.g., booster optical amplifier2102) may be based at least in part on a distance that a downstreamsignal has to travel. For example, the gain may be a function of a fiberattenuation coefficient α, which is a measure of the intensity of theattenuation of a beam of light as it traverses a length of an opticalfiber segment. The unit of measurement of the fiber attenuationcoefficient is decibels (dB) per km (dB/km). For instance, the gain ofbooster optical amplifier 2102 may be adjusted based at least in part onthe attenuation coefficient and length of fiber that the egress opticaldata signal will travel. More specifically, the gain of booster opticalamplifier 102 may be G=e^((2αL)), where α is the fiber attenuationcoefficient, as explained above, and L is the length of the fiber (e.g.,the length of primary fiber 2176 and/or the length of secondary fiber2174). 10GbE DS 2170 may be amplified by booster optical amplifier 2102,and booster optical amplifier 2102 may output 10GbE DS 2178 to port 2164of circulator 2109.

Circulator 2109 may be round baud single or dual stage circulator thatreceives 10GbE DS 2178 on port 2164 and outputs 10GbE DS 2178 on port2188 as 10GbE DS 2180. Circulator 2109 may be similar to circulator2108. That is, the circulator 2109 may allow additional opticalwavelengths to be utilized (e.g., the full array of wavelengths includedin the 48 total channels) and may enable technologies such asQuasi-Coherent and PAM4 (where the DS and UP wavelengths may be closertogether) to be transported in an OCML-MDM infrastructure. Thecirculator 2109 may enable the use of the same wavelength for bothdownstream and upstream and upstream purposes. Circulators may be onedirectional, non-reciprocating (any changes in the properties of thelight caused by passing through the device may not be reversed bytraveling in the opposite direction) devices. Circulators can be used toseparate optical signals that travel in opposite directions in onesingle fiber. Fiber Circulators have high isolation and low insertionloss. 10GbE DS 2180 may be substantially the same as 10GbE DS 2178.10GbE DS 2180 may subsequently be provided to VOA 2115.

VOA 2115 may receive 10GbE DS 2180 at port 2166 as an input, and may beused to reduce the power levels of 10GbE DS 2180. The power reductionmay done by absorption, reflection, diffusion, scattering, deflection,diffraction, and dispersion, of 10GbE DS 2180. VOA 2115 may have aworking wavelength range in which it absorbs all light energy equally.In some embodiments, VOA 2115 may utilize a length of high-loss opticalfiber, that operates upon its input optical signal power level in such away that its output signal power level is less than the input level. Thevariability of the output power level of VOA 2115 may be achieved usinga fiber coupler, where some of the power is not sent to the port thatoutputs, but to another port. Another possibility is to exploit variablecoupling losses, which are influenced by variable positioning of a fiberend. For example, the transverse position of the output fiber or thewidth of an air gap between two fibers may be varied, obtaining avariable loss without a strong wavelength dependence. This principle maybe used for single-mode fibers. VOA 2115 may be based on some piece ofdoped fiber, exhibiting absorption within a certain wavelength range.The VOA 2115 may also be tuned in synchronization with any of thetunable DCMs (e.g., 2112 and/or 2114). That is the tunable DCMs and theVOA 2115 may be tuned for the same transmission distance. The VOA 2115may take 10GbE DS 2180 and output 10GbE DS 2182 at port 2171 to WDM2110.

Upon receiving 10GbE DS 2182, WDM 2110 may be used to multiplex 10GbE DS2182 with one or more PON signals (e.g., XGPON/10GEPON 2182 and GPON2184). 10GbE DS 2182 may be a multi-wavelength optical data signal,wherein the wavelengths comprise the same wavelengths as 10GbE DS 2198.In some embodiments, the wavelengths of the multi-wavelength opticaldata signal 10GbE DS 2182 may be within the conventional c band ofwavelengths, which may include wavelengths within the 1520 nm-1565 nmrange. XGPON/10GEPON 2182 may be a fiber carrying an XGPON/10GEPONoptical data signal with a wavelength within the 1571 nm-1582 nm range.GPON 2184 may be a fiber carrying a GPON optical data signal with awavelength of 1490 nm. The XGPON/10GEPON optical signal may be input tocirculator 2110 on port 2162 and the GPON signal may be input to WDM 110on port 160. WDM 110 outputs an egress optical data signal from port156, which may be a multi-wavelength optical data signal comprising10GbE, signals. WDM 2110 may multiplex 10GbE DS 2182, the XGPON/10GEPONoptical data signal, and GPON optical data signal the same way DWDM 2106multiplexes optical data signals. The egress optical data signal (e.g.,egress optical data signal 2152) may be output on port 2158 of WDM 2110and optical switch 2116 may switch egress optical data signal 2152 outof connector 2118 or connector 2150. In some embodiments, connector 2118may be a primary connector and connector 2150 may be a secondaryconnector or a backup connector. Wavelength monitoring connector 2146may connect connector 2118 to a first port of wavelength-monitoringports 2126, and wavelength monitoring connector 2148 may connectconnector 2150 to a second port of wavelength-monitoring ports 2126.Wavelength-monitoring ports 2126 may monitor the wavelengths in egressoptical data signal 2152 via connector 2146 or connector 2148 dependingon the position of switch 2116. Egress optical data signal 2152 may exitheadend 2101 either via connector 2144 connected to primary fiber 2176or via connector 2142 connected to secondary fiber 2174 depending on theposition of switch 2116. Egress optical data signal 2152 may betransmitted on primary fiber 2176 to a first connector in the field hubor outside plant, or may be transmitted on secondary fiber 2174 to asecond connector in the field hub or outside plant. The field hub oroutside plant may include a MDM with the first connector and the secondconnector.

Also included on the primary fiber 2176 and/or the secondary fiber 2174may be one or more test points (e.g., test points 2214 and 2216corresponding with primary fiber 2176 and test points 2218 and 2220corresponding with secondary fiber 2174) and/or one or more Optical TimeDomain Reflectometry (OTDR) ports (e.g., OTDR ports 2222 and/or 2224).The test points may be used for monitoring downstream and upstreamsignals being transmitted over the primary fiber 2176 and/or secondaryfiber 2174. The OTDR ports may allow for continuous monitoring of fibersin the presence of data for fiber degradation or fiber cuts. If a fibercut happens, the OTDR enables the location to be determined immediately,significantly reducing outages. OTDR functionality may be enabled via aWDM (e.g., WDM 2211 and/or WDM 2212) and an external port (e.g., theOTDR ports 2222 and/or 2224) on the OCML headend 2101 for injecting anOTDR signal (which may be, for example, 1625 or 1650 nm). The WDMs maybe located after the optical switch 2116 so the OTDR monitoring isindependent of which link is carrying downstream traffic. Both the linksmay always have upstream traffic present, (e.g., an MDM may incorporatea 50% splitter which splits the upstream signal evenly between theprimary and secondary fiber). The OCML's OTDR injection ports may bespecified with a degree of required isolation between the OTDR's1625/1650 nm and traffic bearing C-band wavelengths. This traffic couldbe 10G or Coherent 100G/200G, for example. The additional insertion lossassociated with the components required to inject the OTDR pulse and toprotect transmit/receive equipment from the backscattered or transmittedOTDR signals. The additional insertion losses may be ≤0.5 dB and thuscan be easily accommodated within the system link budget. The operationof headend 2101 may also be described by way of the processing ofupstream optical data signals received at headend 2101 from a field hubor outside plant. That is, processing in the opposite signal flowdirection as downstream signal processing described above. In someinstances, the processing of upstream optical data signals may involvethe reverse process of the processing of downstream optical data signalsas described above. That is, the processing may occur starting from theprimary fiber 2176 and/or secondary fiber 2174 and end with the DWDM2106. In some instances, one difference between upstream and downstreamprocessing may be that optical pre-amplifier 2014 and DCM 2114 may beused instead of amplifier 2102 and DCM 2112. However, in some instances,amplifier 2102 and DCM 2112 may also be used in the upstream processingas well, or a combination of any of the aforementioned amplifiers and/orDCMs may be used. Additionally, the functionality of the componentsinvolved in the upstream processing may be the same or similar to thefunctionality of the components involved in the downstream processing.

In processing of upstream optical data signals, a multi-wavelengthingress optical data signal, comprising one or more of a 10GbE opticaldata signal, XGPON/10GEPON optical data signal, and/or GPON optical datasignal, may be an upstream optical data signal received on primary fiber2176 or secondary fiber 2174 depending on the position of switch 2116.Because the multi-wavelength ingress optical data signal is routed toport 2158 of WDM 2110, and may be altered negligibly between connector2144 and port 2158 or connector 2142 and port 2158, depending on theposition of switch 2116, the multi-wavelength ingress optical datasignal may be substantially the same as ingress optical data signal2154. The multi-wavelength ingress optical data signal may traverseconnector 2118 and switch 2116, before entering WDM 2110 via port 2158if switch 2116 is connected to connector 2118. The multi-wavelengthingress optical data signal may traverse connector 2150 switch 2116,before entering WDM 2110 via port 2158 if switch 2116 is connected toconnector 2150. WDM 2110 may demultiplex one or more 10GbE optical datasignals, XGPON/10GEPON optical data signals, and/or GPON optical datasignals from ingress optical data signal 2154. WDM 2110 may transmit theone or more XGPON/10GEPON optical data signals along XGPON/10GEPON 2182to one of PON connectors 2124 via port 2162. WDM 2110 may transmit theone or more GPON optical data signals along GPON 2184 to one of PONconnectors 2124 via port 2160. WDM 110 may transmit the one or more10GbE optical data signals (e.g., 10GbE UP 2180) out of port 2156 to VOA2115, and then to the circulator 2109. The VOA 2115 may serve the samefunctionality in both the downstream and upstream signal processing.That is, the VOA 2115 may attenuate both downstream and upstream trafficdepending on signal transmission distance. The operation of thecirculator 2109 in upstream signal transmission may be the same asduring downstream signal transmission. That is, the circulator 2019 maydirect signal traffic to a respective amplifier (e.g., opticalpre-amplifier 2104).

From circulator 2109, the signal may be transmitted to opticalpre-amplifier 2014. Optical pre-amplifier 2104 may be similar to boosteroptical amplifier 2102. A gain of optical pre-amplifier 2104 may bebased at least in part on a distance that the SONET/SDH egress opticaldata signal has to travel. For example, the gain may be a function of afiber attenuation coefficient α, which is a measure of the intensity ofthe attenuation of a beam of light as it traverses a length of anoptical fiber segment on the SONET/SDH optical network connection. Forinstance, the gain of optical pre-amplifier 2104 may be adjusted basedat least in part on the attenuation coefficient and length of fiber thatthe egress optical data signal will travel. More specifically, the gainof optical pre-amplifier 2104 may be G=e^((2αL)), where α is the fiberattenuation coefficient, as explained above, and L is the length of thefiber (e.g., the length of the fiber of the SONET/SDH optical networkconnection). 10GbE UP 2166 may be amplified by optical pre-amplifier2104, and optical pre-amplifier 2104 may output 10GbE UP 2168 to DCM2114.

In some embodiments, DCM 2114 may be configured to balance positiveand/or negative dispersion that may be introduced to a SONET/SDH egressoptical data signal that may exit headend 2101 from 24×10GbE UP 2188.The SONET/SDH egress optical data signal may be an upstream signal froma field hub or outside plant destined for a MTC. For example, a customerpremise may be connected to the field hub or outside plant and may sendone or more packets via a SONET/SDH network to the field hub or outsideplant which may in turn transmit the one or more packets using 10GbEoptical data signals to headend 2101. The one or more packets may bedestined for a company web server connected to the MTC via a backbonenetwork. Because headend 2101 may be collocated in a STC that isconnected to the MTC via an optical ring network, wherein the connectionbetween the STC and MTC is an SONET/SDH optical network connection, DCM2114 may be configured to compensate for positive and/or negativedispersion on the SONET/SDH optical network connection. That is DCM 2114may be configured to reduce temporal broadening of the SONET/SDH ingressoptical data signal or temporal contraction of the SONET/SDH ingressoptical data signal. DCM 2114 may input 10GbE UP 2168 and may output10GbE UP 2166 to an input of a circulator (e.g., circulator 2108).

The wavelength of 10GbE UP 2166 may be within the conventional c band ofwavelengths, which may include wavelengths within the 1520 nm-1565 nmrange. The one or more XGPON/10GEPON optical data signals may have awavelength within the 1571 nm-1582 nm range, and the one or more GPONoptical data signals may have a wavelength of 1490 nm.

Circulator 2108 may receive 10GbE UP 2166 on port 2192, and may output10GbE UP 2168 on port 2194 as a multi-wavelength upstream optical datasignal (e.g., 10GbE UP 2196). 10GbE UP 2196 is substantially the same as10GbE UP 2168. 10GbE UP 2196 may be received by DWDM 2106, and DWDM 2016may demultiplex one or more 10GbE optical data signals from 10GbE UP2196. Because 10GbE UP 2196 is a dispersion compensated amplifiedversion of the multi-wavelength ingress optical data signal, DWDM 2106may demultiplex the one or more optical data signals into individualoptical data signals in accordance with the individual wavelengths ofany 10GbE optical data signals in the multi-wavelength ingress opticaldata signal. More specifically, 10GbE UP 2196 may be demultiplexed intotwenty four 10GbE optical data signals, each of which may have a uniquewavelength. DWDM 2106 may output each of the twenty 10GbE optical datasignals to each of the transponders of 24×10GbE UP 2188. Each of thetransponders of 24×10GbE UP 2188 may convert a received corresponding10GbE optical data signal, of the 10GbE optical data signals, into acorresponding electrical signal. More specifically, a first transceiverin each of the transponders may convert each of the twenty four 10GbEoptical data signals into the corresponding electrical signal. Each ofthe transponders may also comprise a second transceiver that may convertthe corresponding electrical signal into a SONET/SDH optical data signalwith a corresponding SONET/SDH optical data signal wavelength. In someembodiments, each of the twenty four corresponding SONET/SDH opticaldata signals may have the same wavelength. In other embodiments, each ofthe twenty four corresponding SONET/SDH optical data signals may haveunique wavelengths. The twenty four transponders of 24×10GbE UP 2188 maytransmit the twenty four SONET/SDH optical data signals to the MTC onthe SONET/SDH optical network connection.

FIG. 22 depicts a network diagram 2200 of a back-to-back OCML networkconfiguration, in accordance with the disclosure. The network diagram2200 may include a master terminal center (MTC) 2202, a secondaryterminal center (STC) 2204, and an outside plant 2206. In theback-to-back OCML network configuration, OCML systems (e.g., OCMLsystems 2212, 2213, 2228, 2229, and/or 2240) may be located at both theMTC and the STC. That is, The OCML headend may be located in a centralhub as well as a secondary hub that connects the central hub facility toa field hub or outside plant housing a multiplexer-demultiplexer (MDM)(e.g., MDM 2242 and/or MDM 2244).

Within the network diagram 2200, the MTC 2202 may specifically includeone or more coherent transport platforms (e.g., coherent transportplatform 2208 and coherent transport platform 2210) and one or more OCMLsystems (e.g., OCML system 2212 and OCML system 2213). The coherenttransport platforms may be platforms that may be specifically configuredto transmit coherent signals, which may be special types of opticalsignals capable of transmitting at higher capacities (e.g., 100 Gbps andabove) for long distances (e.g., greater than 80 km). The OCML systems2212 and/or 2213 may be the same as any of the OCML systems (which maybe referred to as headends) described herein, such as the OCML headend101 with respect to FIG. 1 or the OCML headend 2201 with respect to FIG.21, as well as any other OCML system described herein.

The STC 2204 may also include a first set of one or more OCML systems(e.g., OCML systems 2228 and 2229), one or more coherent transportplatforms (e.g., coherent transport platform 2232 and coherent transportplatform 2234), and may additionally include one or more switches (e.g.,switches 2236 and 2238), and a second set of one or more OCML systems2240. Similar to the coherent transport platforms of the MTC, thecoherent transport platforms of the STC may be platforms that may bespecifically configured to transmit coherent signals, which may bespecial types of optical signals capable of transmitting at highercapacities (e.g., 100 Gbps and above) for long distances (e.g., greaterthan 80 km). The STC 2204 may also include one or more switches (e.g.,switch 2236 and/or switch 2238), which may receive as inputs signalsfrom the coherent transport platforms 2232 and/or 2234 and output thesignals to one or more of the set of OCML systems 2240. The OCML systems2228, 2229, and/or 2240 may be the same as any of the OCML systems(which may be referred to as headends) described herein, such as theOCML headend 101 with respect to FIG. 1 or the OCML headend 2201 withrespect to FIG. 21, as well as any other OCML system described herein.

In some embodiments, the OCML systems at the MTC (e.g., OCML systems2212 and 2213) may multiplex one or more signals received from thecoherent transport platforms (e.g., coherent transport platform 2208 and2210), as well as other signals from other sources, may send themultiplexed optical signals over fibers (e.g., fibers 2224 and 2226)from the MTC to the OCML systems (e.g., OCML systems 2228 and 2229) atthe STC, where the multiplexed optical signals may be demultiplexed.Thus, the OCML systems at the STC may be performing demultiplexingrather than MDMs. To accomplish back-to-back OCML optical signaltransmission sequence, the OCML systems at the MTC may process opticalsignals in a downstream manner, and the OCML systems at the STC mayprocess optical signals in an upstream manner. For example, The OCMLsystems at the MTC may receive one or more optical signals at one ormore DWDMs (e.g., DWDM 2216 and 2218), which may multiplex the signalsinto a combined optical data signal. The combined optical data signalmay then be send to downstream circuit elements 2200. The downstreamcircuit elements 2200 may simply be a representation of any circuitelements that may be included in an OCML system as described herein (forexample with reference to the OCML headend 101 of FIG. 1 or the OCMLheadend 2101 of FIG. 21). The multiplexed optical data signal may thenbe outputted to the OCML systems at the STC through one or more outputfibers 2224 and 2226. The reverse processing may occur at the OCMLs atthe STC. For example, The multiplexed optical data signals may bereceived at a switch of the OCMLs at the STC, may be sent to downstreamcircuit elements 2230, and then may subsequently be sent to the DWDMs(e.g., DWDM 2250 and 2252). The DWDMs may demultiplex the multiplexedoptical data signals, and provide the demultiplexed optical data signalsto one or more coherent transport platforms at the STC (e.g., coherenttransport platform) 2232 and 2234.

The outside plant 2206 may receive signal outputs from the OCML systems2240 located at the STC 2204 at one or more MDMs (e.g., MDM 2242 and MDM2244). The MDMs may receive optical data signals from the second set ofone or more OCML systems 2240 at the STC 2204, demultiplex the opticaldata signals, and transmit the demultiplex signals to one or more remotePHY nodes (RPDs) 2246. The MDMs may also be capable of receiving signalsfrom the RPDs 2246, multiplexing the signals, and providing the signalsto the OCML systems 2240. That is, the MDM may be capable of performingboth multiplexing and demultiplexing functionality.

The OCML systems described with respect to FIG. 22 (e.g., OCML systems2212, 2228, and/or 2240) may be the same as any of the OCML systems(which may be referred to as headends) described herein, such as theOCML headend 101 with respect to FIG. 1 or the OCML headend 2201 withrespect to FIG. 21. For example, as depicted in FIG. 22, the OCML 2212may include at least one or more DWDMs (e.g., DWDM 2216 and DWDM 2218),one or more downstream circuit elements 2220, one or more upstreamcircuit elements 2222, and one or more fibers (e.g., downstream fiber2224 and upstream fiber 2226). For simplicity, the OCML systems in FIG.22 may be depicted including downstream and upstream elements that mayrepresent some or all of the circuit elements described with respect toOCML system of FIG. 1 or OCML headend 2201 with respect to FIG. Forexample, with respect to the OCML of FIG. 21, the downstream andupstream circuit elements may include one or more circulators, one ormore DCMs, one or more amplifiers, one or more VOAs, and one or moreWDMs. However, these are merely examples, any of the OCML circuitelements described herein may also be included.

In some embodiments, the components of the network diagram 2200 may becapable of transmitting signals at rates of up to 25 Gbps or higher.Transmission at these rates may be possible between any of thecomponents of the network diagram 2200, such as the MTC 2202, STC 2204,and the outside plant 2206, for example, and ultimately, customer homesand commercial locations. Transmission at such rates may be possiblethrough the use of one or more different types of optical detection andmodulation schemes. The detection scheme may be classified into threegroups, including: 1) direct detection, 2) quasi-coherent, and 3)coherent detection schemes.

Modulation schemes that use direct detection may include at leastnon-return to zero (NRZ), pulse amplitude modulation (PAM4), andduo-binary. Systems that use direction detection may use intensitymodulation at the transmitter side (and direct detection at the receiverside), which may be deemed “intensity modulated direct detection”(IM-DD). Of the three aforementioned modulation schemes that may be usedwith direct detection systems, NRZ is an “on/off keying” (OOK)modulation scheme, duo-binary is a special OOK scheme that is moreresilient to dispersion, and PAM4 may be used for optical componentssuitable for smaller form factors. PAM4 may also be associated with adrastically reduced power consumption and low latency.

Quasi coherent systems typically increase receiver sensitivity more thanten times over a conventional optical receiver and may offer vastsimplification over conventional coherent schemes. Quasi-coherentreceivers may use a local oscillator to produce signal gain, but may notneed to extract phase information, which may result in the highersensitivity. Instead of using potentially expensive digital signalprocessing (DSP) algorithms, quasi-coherent receivers use envelopedetection for signal extraction. While the detection system may beclassified as coherent, NRZ or PAM4 modulation schemes may be used forhigh capacity data rates at lower cost and power consumption than fullcoherent schemes. Because no DSP is required, only analog signalprocessing is required, which may result in lower power consumption andlow latency. Quasi-coherent schemes may also be able to transportdifferent bi-directional wavelengths on the same fiber, withoutrequiring a second laser as may be required in a full coherent scheme.

Transmission at such rates to end customers may also be possible throughthe use of an extended spectrum Data Over Cable Service InterfaceSpecification (DOCSIS) networks. For example, typical DOCSIS networksmay use a bandwidth of approximately 1.2 GHz. The extended spectrumDOCSIS network may, however, include an increased bandwidth of up to 1.8GHz, 3 GHz, or an ever larger bandwidth beyond 3 GHz. By doing this,signal transmission through a DOCSIS network may be reduced by one ormore wavelengths because more bandwidth is provided through the expandedspectrum.

It should be noted that these heightened transmission rates may beapplicable to any of the networks described herein, such as, forexample, network diagram 2300 described with reference to FIG. 23, aswell as any descriptions associated with any of the other FIGs describedherein.

FIG. 23 depicts a network diagram 2300 of an OCML headend and outsideplant, in accordance with the disclosure. The network diagram 2300 maybe an alternative to the network diagram 2200 depicted in FIG. 22, orany other network diagrams depicted herein. The network diagram 2300 mayinclude a MTC 2302, a STC 2304, and an outside plant 2306. In theparticular embodiments depicted in FIG. 23, OCML systems (e.g., OCMLsystems 22320, 2322, and/or 2336) may be located at both the MTC 2302and the STC 2304). That is, The OCML headend may be located in the MTC2302 itself as well as a secondary terminal center (STC) 2304 thatconnects the MTC facility to a field hub or outside plant housing amultiplexer-demultiplexer (MDM) (e.g., MDM 2338 and/or MDM 2340).

Within the network diagram 2300, the MTC 2302 may specifically includeat least one or more routers 2310 feeding one or more switches 2312and/or one or more coherent transport platforms (e.g., coherenttransport platform 2316 and coherent transport platform 2318), one ormore CMTS platforms 2314, one or more coherent transport platforms(e.g., coherent transport platform 2316 and coherent transport platform2318), and one or more OCML systems (e.g., OCML system 2320 and OCMLsystem 2322). The coherent transport platforms may be similar to thecoherent transport platforms described with reference to FIG. 22 (e.g.,coherent transport platforms 2208, 2210, 2232, and/or 2234). That is thecoherent transport platforms may be platforms that may be specificallyconfigured to transmit coherent signals, which may be special types ofoptical signals capable of transmitting at higher capacities (e.g., 100Gbps and above) for long distances (e.g., greater than 80 km). The OCMLsystems 2320 and/or 2322 may be the same as any of the OCML systems(which may be referred to as headends) described herein, such as theOCML headend 101 with respect to FIG. 1 or the OCML headend 2201 withrespect to FIG. 21.

The STC 2304 may also include one or more MDMs (e.g., MDMs 2324 and2326), one or more coherent transport platforms (e.g., coherenttransport platform 2328 and coherent transport platform 2330), and mayadditionally include one or more switches (e.g., switches 2332 and2334), and one or more OCML systems 2336. Similar to the coherenttransport platforms of the MTC, the coherent transport platforms of theSTC may be platforms that may be specifically configured to transmitcoherent signals, which may be special types of optical signals capableof transmitting at higher capacities (e.g., 100 Gbps and above) for longdistances (e.g., greater than 80 km). The STC may also include one ormore switches (e.g., switches 2232 and/or 2314) which may receive asinputs signals from the coherent transport platforms 2328 and/or 2330and output the signals to one or more of the set of OCML systems 2336.In some instances, any of the coherent transport platforms may beintegrated into any of the switches (e.g., coherent transport platforms2316 and/or 2318 may be integrated into switch 2310 and/or coherenttransport platforms 2328 and/or 2330 may be integrated into switches2332 and/or 2314). The OCML systems 2336 may be the same as any of theOCML systems (which may be referred to as headends) described herein,such as the OCML headend 101 with respect to FIG. 1 or the OCML headend2201 with respect to FIG. 21.

The outside plant 2306 may receive signal outputs from the OCML systems2336 located at the STC 2304 at one or more MDMs (e.g., MDM 2338 and MDM2340). The MDMs may receive optical data signals from the second set ofone or more OCML systems 2336 at the STC 2304, demultiplex the opticaldata signals, and transmit the demultiplex signals to one or more remotePHY nodes (RPDs) 2342. The MDMs may also be capable of receiving signalsfrom the RPDs 2342, multiplexing the signals, and providing the signalsto the OCML systems 2336. That is, the MDM may be capable of performingboth multiplexing and demultiplexing functionality.

FIG. 24 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure. At block 2402 the OCMLheadend receives, by a dense wave division multiplexer (DWDM), one ormore optical data signals. At block 2404, the OCML headend combines, bythe DWDM, the one or more optical data signals. At block 2406 the OCMLheadend outputs, by the DWDM, the combined one or more optical datasignals to a first circulator. At block 2408 the OCML headend combines,by the first circulator, the second optical data signal and one or morethird signals, and outputs an egress optical data signal to an opticalswitch. At block 2410 the OCML headend outputs, by the optical switch,the egress optical data signal on a primary fiber.

FIG. 25 depicts a process of transmitting optical signals with the OCMLheadend, in accordance with the disclosure. At block 2502 an operationof receiving, by a first optical communications module link extender(OCML) system at a central hub one or more optical data signals isperformed. At block 2502, an operation of sending, by the first OCMLsystem, the one or more optical data signals to a second OCML system ata secondary hub is performed. At block 2506, an operation of outputtingthe one or more optical data signals on a primary fiber is performed.

What is claimed is:
 1. A cable network system comprising: a masterterminal center (MTC) comprising a first optical communications modulelink extender (OCML) system, the first OCML system comprising: a firstdense wave division multiplexer (DWDM) that is configured to receive oneor more first optical data signals at a first input of the OCML, combinethe one or more first optical data signals, and output a second opticaldata signal; a first wave division multiplexer (WDM) that is configuredto receive the second optical data signal from the first DWDM and one ormore passive optical network (PON) signals from a second input of thefirst OCML system, and output a third optical data signal; and a firstoptical switch that is configured to receive the third optical datasignal from the first WDM and output a fourth optical data signal to afirst fiber, wherein the master terminal center (MTC) further comprisesa first coherent transport platform, a second coherent transportplatform, and a second OCML system, wherein the first OCML system isfurther configured to receive a first coherent data signal from thefirst coherent transport platform, wherein the second OCML system isfurther configured to receive a second coherent data signal from thesecond coherent transport platform, wherein the first coherent transportplatform and the second coherent transport platform are configured toreceive the first coherent data signal and the second coherent datasignal from a switch at the MTC, and wherein the first coherent datasignal and the second coherent data signal are at different datatransfer speeds; a secondary transport center (STC) located downstreamin the cable network from the MTC and comprising a third OCML system incommunication with the first OCML system, the third OCML systemcomprising: a second optical switch that is configured to receive thefourth optical data signal from the first fiber and output a fifthoptical data signal; a second WDM configured to receive the fifthoptical data signal from the second optical switch and output a sixthoptical data signal; and a second dense wave division multiplexer (DWDM)that is configured to receive the sixth optical data signal, demultiplexthe sixth optical data signal, and output a seventh optical data signal;and an outside plant located downstream in the cable network from theSTC and comprising a multiplexer-demultiplexer (MDM) that is configuredto receive the seventh optical data signal from the second DWDM.
 2. Thesystem of claim 1, wherein the secondary transport center (STC) furthercomprises a switch.
 3. The system of claim 1, wherein the first OCMLsystem and second OCML system further comprise: a tunable dispersioncompensation module (DCM) configured to: receive the second optical datasignal from the DWDM and remove interference between adjacent symbols inthe second optical data signal; and output an eighth optical datasignal.
 4. The system of claim 3, wherein the tunable DCM is tuned to asignal transmission distance.
 5. The system of claim 4, furthercomprising: a booster optical amplifier communicatively coupled to thetunable DCM, the booster optical amplifier being configured to receivethe eighth optical data signal, amplify the eighth optical data signal,and output a ninth optical data signal.
 6. The system of claim 5,wherein the booster optical amplifier is an erbium doped fiberamplifiers (EDFA) or a semiconductor optical amplifier (SOA).
 7. Thesystem of claim 5, wherein the first WDM is further configured toreceive the ninth optical data signal from the booster optical amplifierand output a tenth optical data signal.
 8. The system of claim 7,further comprising: a variable optical amplifier (VOA) configured toreceive the tenth optical data signal from the booster opticalamplifier, adjust a power of the tenth optical data signal to a firstlevel, and output an eleventh optical data signal.
 9. The cable networksystem of claim 1, wherein the one or more first optical data signalsinclude one or more Ethernet signals, and wherein the first WDM isfurther configured to: receive an upstream data signal including acombined Ethernet signals and one or more PON signals; output thecombined Ethernet signals at a first output; and output the one or morePON signals at a second output.
 10. A method for transmitting one ormore optical data signals along a cable network, the method comprising:receiving, by a first optical communications module link extender (OCML)system at a master terminal center (MTC), one or more first optical datasignals, wherein the first OCML system comprises a first dense wavedivision multiplexer (DWDM) that is configured to receive the one ormore first optical data signals at a first input, combine the one ormore first optical data signals, and output a second optical datasignal, wherein the first OCML system further comprises a first wavedivision multiplexer (WDM) that is configured to receive the secondoptical data signal from the first DWDM and one or more passive opticalnetwork (PON) signals from a second input of the first OCML system, andis further configured to output a third optical data signal; sending, bythe first OCML system, the third optical data signal to a second OCMLsystem at a secondary transport center (STC) located downstream in thecable network from the MTC; and sending, by the second OCML system, afourth optical data signal to an outside plant located downstream in thecable network from the STC, the outside plant including amultiplexer-demultiplexer (MDM) in communication with the second OCMLsystem, wherein the master terminal center (MTC) further comprises afirst coherent transport platform, a second coherent transport platform,and a third OCML system, wherein the first OCML system is furtherconfigured to receive a first coherent data signal from the firstcoherent transport platform, wherein the third OCML system is furtherconfigured to receive a second coherent data signal from the secondcoherent transport platform, wherein the first coherent transportplatform and the second coherent transport platform are configured toreceive the first coherent data signal and the second coherent datasignal from a switch at the MTC, and wherein the first coherent datasignal and the second coherent data signal are at different datatransfer speeds.
 11. The method of claim 10, wherein the first OCMLsystem and second OCML system comprise: a tunable dispersioncompensation module (DCM) configured to receive the second optical datasignal, remove interference between adjacent symbols in the secondoptical data signal, and output a fifth optical data signal; a boosteroptical amplifier configured to receive the fifth optical data signal,amplify the fifth optical data signal, and output a sixth optical datasignal; a second WDM configured to receive the sixth optical data signaland output a seventh optical data signal; and a variable opticalamplifier (VOA) configured to receive the seventh optical data signal,adjust a power of the seventh optical data signal to a first level, andoutput an eighth optical data signal.
 12. A cable network systemcomprising: a master terminal center (MTC) comprising a first opticalcommunications module link extender (OCML) system; and a secondarytransport center (STC) located downstream in the cable network from theMTC and comprising a second OCML system in communication with the firstOCML system, wherein the first OCML system and second OCML systemcomprise: a dense wave division multiplexer (DWDM) that is configured toreceive one or more optical data signals at a first input of the firstOCML system or the second OCML system, combine the one or more opticaldata signals, and output a combined optical data signal; a firstcirculator communicatively coupled to the DWDM, the first circulatorbeing configured to receive the combined optical data signal from theDWDM and one or more passive optical network (PON) signals received froma second input of the first OCML system or the second OCML system andoutput the combined optical data signal and the one or more PON signals,wherein the master terminal center (MTC) further comprises a firstcoherent transport platform, a second coherent transport platform, and athird OCML system, wherein the first OCML system is further configuredto receive a first coherent data signal from the first coherenttransport platform, wherein the third OCML system is further configuredto receive a second coherent data signal from the second coherenttransport platform, wherein the first coherent transport platform andthe second coherent transport platform are configured to receive thefirst coherent data signal and the second coherent data signal from aswitch at the MTC, and wherein the first coherent data signal and thesecond coherent data signal are at different data transfer speeds; anoptical switch that receives the combined optical data signal and one ormore PON signals and outputs the combined optical data signal and one ormore PON signals to a first fiber; and an outside plant locateddownstream in the cable network from the STC and comprising amultiplexer-demultiplexer (MDM) that is configured to receive thecombined optical data signal and one or more PON signals.
 13. The cablenetwork system of claim 12, wherein the secondary transport center (STC)further comprises a fourth OCML system.
 14. The cable network system ofclaim 12, wherein the secondary transport center (STC) further comprisesa switch.
 15. The cable network system of claim 12, wherein the firstOCML system and second OCML system further comprise: a tunabledispersion compensation module (DCM) configured to: receive the combinedoptical data signal from the DWDM and remove interference betweenadjacent symbols in the combined optical data signal; and output asecond optical data signal.